I have never played any of those - shall i play the gate to infity if cheap?

They have fixed the mistakes/omissions,it has a deeper/longer story,more and harder missions,all pokemon are recruitable,you face all the legendaries,I can say more but i don't want to expatiate....

However,at least the fact that PSM includes what new 6th gen and Pokemon X/Y brought,doesn't lure you?Don't let the underwhelming(compared to its predecessors) gates to infinity to prejudice you and not get this diamond which implies the return to the roots of the series...o

I thought you were a huge fan o pokemon,I don't mean that you're blind and that you would by anything named pokemon even if it's bad but you can't resist to that great game,especially given your fierce love about pokemon!:P

If you want to get a start with the series, play Explorers of Time or Darkness, they are definitely among the DS' best games. They and the rescue team games are both great. You can get them for like $10 now too. Gates to Infinity was absolutely awful by comparison, avoid it like the plague.

OT: I'm now six hours into the game and it is fantastic. Much much better than Gates; plays like the first two sets, but the story is slightly weaker than EoT/D, closer to the rescue team games. 

There's been absolutely nothing that leads me to believe the story has been improved. I don't nlindly buy anything pokemon makes.

nice to hear!! I was kind of addicted to the first games, great story and everything but didn't play the rest

probably going to try Explorers since it sounds great, and skip the 3DS one because of no time and negative comments

being able to get any of the 720 pokemon sounds promising on its own, so I must join the hype :D

Just finished the main storyline of the game, so I'll give my impressions on the game here. If you don't want ANYTHING gameplay wise spoiled, don't read on. Story stuff will be put in spoiler tags if I write anything about it.

• Getting throught the main storyline took me about ~30 hours, pretty average for a Pokemon game, but compared to the previous mystery dungeon games (not including gates to infinity) it felt a bit short.
• Graphically, the game is rather... dull? There are a few parts in the game where I was amazed visually, but overall it doesn't have the same life that the artstyle of the DS games did.
• Soundtrack is however, excellent as always. Background music in the dungeons and cities is great and it never gets tiring to listen to. Jukebox feature is there with the ability to listen to a few tracks from past games, but not enough imo. A feature to change these tracks with the preset ones in dungeons would be the only improvement I could ask for in this respect.
• Gameplay is standard dungeon fare, that is, well executed and a return to its classic excellent form after gates. The return of the belly mechanic and the ability to group attack a single foe makes some of the more troublesome foes easier to take down.
• The dungeons themselves are quite short compared to the DS games. Most dungeons are 9-10 floors, with later dungeons having a rest area with access to the item box. This may have contributed a bit to the feelings of shortness I had throughout the game. Dungeons unlocked post-game are much longer than the storyline ones, which made up for this a bit.
• The first ~6-7 hours of the game are spent not as an exploration team, but in the Pokemon School. As far as I can see this was set up as a tutorial of sorts for those new to the series, but this portion felt quite dragged out. It does set up a few things for the later story, but the very linear feel to this section detracted from the feel of the game for me.
• Once you're an exploration team, you have the ability to take missions on by your 'connection orb' and by completing these missions, you recruit whoever asked you to complete the mission, and often many more pokemon, to your team.  Honestly, I didn't like this very much. Having the ability to recruit Charizard after roughly 20 minutes as an exploration team is cool and all, but I never really used him as it felt cheap just crushing all in my path.
• In saying this however, many later dungeons, especially those on the other (not water) continents, practically require you bring along these hugely powerful pokemon; even then, they aren't usually enough. In these later dungeons, there are many wild Pokemon who are armed with moves like Hydro Pump, Earthquake and Boomburst who can OHKO practically any Pokemon on your team unless you strike first. This felt pretty cheap to me as there were a few times where I was attacked with one of these moves by a Pokemon outside of the range of sight, so you have no prior indication that they are there before getting OHKO'ed.
• Having the ability to rescue yourself using other members of your team via Pelipper island takes the sting out of this cheapness a bit, but its still an annoyance. (Team members you use in the rescue missions gain EXP and items you get while rescuing yourself are sent to the item box)
• Team members can't be taken on missions two days in a row. This was one of things I found most annoying. I want to have Quagsire on my standard team and take him on every mission? Nope, he's resting today, sorry! I can see that they did this to make you try more Pokemon out, but this is just an annoyance, really.
• The story in the game is... good. As I said earlier, the dragged out "tutorial" part of the game is rather boring, but it does set up later game events. The school dynamic felt rather run of the mill, but it does a good job of setting you and your partner up as 'outsiders' and laying the foundation for your partnership. The "legendaries being turned into stone and world being thrown into the sun" main plot of the game is interesting and done well, other than feeling slightly rushed.

Nope. Always hated the mystery dungeon games. Actually I hate pokemon games in general. The new ones at least.

The old ones are freaking classic though.

Nope, no references to the other games' stories are made throughout the game so you can just jump right in with this one. 

I like the way you think!
Basically I've been hyped for this game since I heard it was coming out. The first two games the series are amazing with GTI being the odd one out (as you said).
Hoping for the story to be much better this time around, and being able to recruit all the Pokémon up to this point is also a plus for me.

Get either Stella Glow or Legend of Legacy. Both of those come with Pre-order bonuses (Or launch bonuses) so yeah. I think those will be more worth it due to that.