I liked the light/dark world concept in MPII, but another possibility could have to been to expand on one world instead of the using the same world twice. Also, I don't know what the general opinion is of the multiplayer, but I think it could have been replaced with more main game.

You basically listed every single room I mentioned. As for the others (particularly the Sanctuary bridge), the problem is that while they're "open" in the sense that they look open, there isn't much manueverability in them. You're still stuck with very much one way to go. The bridge that opens into Sanctuary is a fantastic example of this; what should be a very open room is instead simply a linear, straightforward bridge with a single spider ball track that can be accessed later on. Prime tends to leave platforms around and encourage the player to jump all over the rooms, whereas the few "open" rooms in Echoes lack this sense of freedom.

Allow me to illustrate with an example. Take the two largest rooms from both games, that being the opening room in Phendrana and the Sanctuary Temple. Prime handles the opening room to Phendrana quite well; before you can leave the area, you've had to explore all over it. You've jumped on the platforms, headed on the cliffside, smashed through a gate on the wall, and probably entered a few doors.  Sanctuary Temple, meanwhile, despite being the biggest room in the game, only consists of only a single passageway from the bottom to the top with a few jumps required. The rest is entirely empty space; there aren't even any secrets hidden at the bottom to discover. What this does is keep the sense of cramped, smaller environments intact; you still feel like you're exploring a minimalistic environment since there's nothing really to do except follow the standard path set forth, whereas Prime does a much better job of getting the player to explore the world it puts forth, making it feel much more open in comparison.

I agree that Magmoor and the Phazon Mines are, for the most part, very cramped areas; and there's nothing wrong with that. It's when a game's level design is almost entirely closed in and cramped where things start to get annoying. Even the smaller rooms in the Phazon Mines tend to do a better job of encouraging exploration than the larger rooms in Echoes, however. Perhaps a lot of this has to do with the fact that many of the larger rooms in Echoes require powerups or other items that you get later on in the game (this is going to sound weird, but bear with me) before you can actually navigate them in any way besides just following a straightforward, linear path. The opening room in Agon Wastes, for instance, has a number of platforms that you can use as a shortcut, but you can't take advantage of these until after getting the Space Jump. The "bridge room" (the first picture you linked) can only be traversed on the bottom floor until you find a panel to activate a kinectic orb cannon. The Dark World in particular has a nasty habit of keeping you from exploring large parts of it by blocking off doors with powerups acquired much later. Part of this I'm fine with; withholding certain parts of the area until certain powerups are discovered is certainly a big piece of the Metroid formula; but Echoes doesn't just withhold parts of the area, it withholds ways to get around the same rooms you're in already, making the moving around process a very linear one and one that feels cramped and contained compared to the freedom Prime offered in this regard.

No, I listed many you didn't mention and only after a 5 minute search. That big field in Phendrana drifts is super annoying because if you miss the jump to a certain room on a higher ledge once you need to backtrack and redo everything. If that's your example of good level design then I don't want any of it.

I fail to see how the first Prime has more open and less cramped level design.

Prime was really, the only great Metroid Prime game out there. Echoes sucked and Corruption was average.

Even so the whole trilogy shared flaws with the enemy a.i. the pirates would just run around then stand still then shoot, sometimes they would go all suicidal and run towards you to shoot you in the face risking their own already low life points.

The fetchquest were pretty lame as well but i started to dig the hints the second time around.

I liked the motion controls in Corruption and the silly bit of story but the cheap boss battles and the tacked on Phazon enemies kinda blew it.

Echoes is just a huge and boring flaw.

http://www.metacritic.com/game/gamecube/metroid-prime-2-echoes

http://www.metacritic.com/game/wii/metroid-prime-3-corruption

Seems you're in the minority here. Look at both the critic and userscores. As for cheap bosses... Just no. How many sixth gen games do you know that had great A.I.? Saying a game sucks without giving proper arguments is the only thing that sucks here!

Please just use links if your pictures are going to be that big.

Anyway, it would helpful to read my entire post instead of just quoting one line and not going on. The actual paragraph continued...

"As for the others [read: the other rooms that I did not address] (particularly the Sanctuary bridge), the problem is that while they're "open" in the sense that they look open, there isn't much manueverability in them. You're still stuck with very much one way to go. The bridge that opens into Sanctuary is a fantastic example of this; what should be a very open room is instead simply a linear, straightforward bridge with a single spider ball track that can be accessed later on. Prime tends to leave platforms around and encourage the player to jump all over the rooms, whereas the few "open" rooms in Echoes lack this sense of freedom."

My last point is basically nothing but this argument, but to summarize simply having a room that is "big" does not mean that the level design is not restrictive and/or cramped. The vast majority of the "big" rooms in Echoes are filled with basically nothing to explore at all (see Agon/Torvus/Sanctuary Temple, i.e. the three biggest rooms in the game) or force the player down a single pathway that they cannot stray from (see Sanctuary Bridge). There is very little to actually explore.

That big field in Phendrana drifts is super annoying because if you miss the jump to a certain room on a higher ledge once you need to backtrack and redo everything. If that's your example of good level design then I don't want any of it.

...I think I know what jump you're talking about, and honestly, if you miss that jump, then I really don't know what to say to you. There may not be an easier jump in the game to make. Regardless, if you want to talk about annoying level design, Phendrana's pales in comparison to something like the underwater segments of Torvus Bog, where you're frequently forced into deep pools of water multiple times in the subterranian section with poor visibility and movement that make navigation an absolute chore. Honestly, you could fall off the ledge twice and probably get through that segment quicker than you'd get through the pre Gravity Boost section.

Enemy AI is actually pretty good for sixth gen games, with the only real exception being in Prime that certain Pirate groups won't aggro if you're shooting Pirates that don't belong to their specific "group."

Not sure what the "cheap boss battles," "tacked on Phazon enemies," or the flaws with Echoes are. Care to elaborate?

I am in the minority but even the designer of the Prime games thinks Echoes stinks! (actually he hates all of them) I didnt like the whole travel through light and dark world use light on dark and dark on light thing.

Also the tacked on multiplayer...Actually i had more fun with this than the boring single player mode.

Uhmm FEAR? Half Life 2? Killzone? Maybe Halo even t. All these shooters had great enemy A.I. especially Fear.

Cut down on the quote trees. Great argument about the jump thing. I could say the same about you and Torvus Bog. You're only once forced into the water in Torvus Bog until you enter the submerged temple (a section that lasts about a minute and is very straightforward). So that means you failed easy platforming challenges. The submerged temple wasn't too bad either. The only flaw is that there should have been a saveroom right before you fight the boss (and the boss is a flaw as well as he's annoying). Once you get the gravity boost you feel like a badass because things are much easier now. I think that's great design how the game makes you feel when you get a new powerup. The underwater spaceship in Prime 1 was rather annoying as well. To then find out I need to get to the final room of it again because an artifact is hidden there! Such an annoying part of the game. Very little to explore? There's just as much exploration in Prime 2 as Prime 1. There are in fact more energy tanks to find. I'm not sure about missiles though. The maps tell you all you need to know. I can't make it much clearer than that. Claustrophobic and cramped level design means small corridors. I can only think of Magmoor Caverns that fits that description. Besides, the game is supposed to be like that. It's called Metroid for a reason. Metro + Android. Metro = underground corridors.

Apologies on quote trees.

All I'm talking about on Torvus Bog is the subterranian section; and you're forced underwater on numerous occasions there. You have to go underwater initially when you arrive to enter the seeker missile door (before the Dark Samus cutscene), you have to jump in again after the cutscene, you have to go underwater to overturn a couple of platforms, you have to go in once again to enter and exit a dark portal, and you have to go back in once more to travel to the Gravity Boost. That's a grand total of 5 segments where you are forced into the water without the Gravity Boost. None of this is even accounting for the potential for falling in, and even if it is linear, it takes far more than a minute to get through and it's a pain to simply traverse.

I would agree with you about the downed frigate, but luckily, Prime gives you the Gravity Suit for the entirety of it. Also...there's no artifact hidden in the frigate. Not entirely sure what you're talking about there. There's one in the life grove, but there's far easier ways to access that then traversing the entirety of the frigate.

I'm going to try and make the point about exploration one more time; I'm honestly not sure how I can make this any clearer. In regards to the "big" rooms in Prime 2, the majority of them have little to nothing to actually explore. They simply require you to follow a straightforward path and there's very little else to do. The maps of the two games look similar in terms of room "bigness," but the vast majority of the bigger rooms shown off on the map have so little to do in them that it simply keeps them from adding to any real feel of exploration. That's the argument.