Mass Effect 3 is an uneven experience. What annoys me the most about it is that people focus on the endings and gloss over the other flaws in the game. The gameplay is execllent. However the quest system and quest log is the worst in the entire series. The quest log doesn't update properly at each step of the quest like the previous two games. Worse the vast majority of the side consists of Commander Shepard easedropping on peoples conversations and then just showing up and saying "You know that thing you were talking, pick it up in Dock D24".
The conversation system is the most limited in the series. This is a real shame because they finally got the Renegade/Paragon system right in ME3. With ME3's setup you can answer questions however you like because the reputation system prevents you from being locked out of conversation options if you didn't go pure Paragon or pure Renegade. The problem is you don't have the options you did previously. Unlike the first two game, ME1 especially, you don't have the conversation options you had before. You used to have a minimum of 3 and sometimes as many 6 opitions. In ME3 you usually only have two options. A paragon or renegade response. Ocassionally you'd have a neutral option. To make matters worse, ME3 has tons of auto dialogue. You'd pick one of the two options and Shepard would practically give a speech before you got another chance to pick a choice. Shepard was the players character in the first two games. Biowares character in the third.
This was part of the reason, I finished ME3 the least amount of times out of the trilogy. Only managed 3 complete playthroughs. That sounds like a lot but I finished ME1 on 360 15 times and 3 times on PC. I finished ME2 a dozen times. I basically had Shepard for every major option and gave them their own personality. When I got to ME3, my Shepards were the same. So I stopped playing. I too thought wasn't that bad of a game except for the endings until I go to my second playthrough and realized how limited the conversation options were. If your character was in a romance with an ME2 character you the got shaft. It's worst for players that played a female Shepard. I'm member of another Bioware centric forum, unlike here we have several women members there. If a female Shepard romanced Kaidan but saved Ashley in ME1. She'd have no straight romance options in ME3 unless she picked Garrus in ME2. Otherwise Garrus hooks up with Tali, Thane dies, and Jacob runs off with Lady Hawke from Dragon Age 2. Of course they did get the option to date rape Vega during Citadel. I'm not kidding. Shepard can get him drunk and take advantage him.
With the exception of Legion and Mordin, the ME2 cast didn't matter. None of them became squad mates. Miranda's ME3 Story arc was a rehash of her loyalty mission in ME2 stretched throughout the whole game. They forgot Jacob was biotic. He and his team are fighting for their lives and doesn't use his biotics at all. It's especially bad when runs through live gunfire and doens't use his barrier. I realized that making every squad member available would have costly and daunting, but they could have wrote legitmate reasons for them to not help you. Samara, Jacob, Miranda, Zaeed, and Kasumi all have poor excuses why they won't join you. It's clear that new writers didn't read up on the works of the prior writers. I'm ranting here but I'll give one small example of what I'm talking about. Kasumi tells Shepard "I wont' let you rope me into another suicide mission". A)The Illusive Man hires her. B)She knows it's a suicide mission from the beginning.
The game was very uneven. Tuchanka and Rannoch were very well written. Most of the rest of the game was not. On the beam run Shepard enters before Anderson, but some how ends up behind him. The audio talks if there are multiple paths but there is only one. In ME1 the reason the Reapers go after the Citadel is because A)It allows them to bring their entire fleet to seat of the Galaxy at once and B)They can shut down the entire Mass Relay system from the Citadel. They gain control of the Citadel in ME3 but they don't shut down the relays. They make a point telling you how the Reapers shut down the relays and systematically hunt down advanced life system by system. In ME3 they forget this for some reason. In ME2 they make a point of showing you how the destruction of a Mass Relay is the equivalent of a Supernova and wipes out the whole star system. In the original endings, when you activate The Crucible it blows up all the Mass Relays which means you'd would have wiped out most of the life in the Galaxy.
Heck I could rant on this all night. ME3 is a great game from a purely gameplay standpoint. However the narrative is very poor, they forget their own lore at several points, forget about the abilities of characters, or flat out make them completely out of character. Ashley being the biggest example. They dressed her up like Miranda when she's tomboy and tells you in ME1 that she'd never dress that way. If you play purely for the game play or don't care much for the story. ME3 is great game. If you played series from start to finish, really enjoyed the story and characters, then ME3 is a deeply flawed game. The inconsistencies stick out like a sore thumb and you're left to wonder what could have been.