My only problem with the game, other than the atrocious ending obviously, is the lack of squadmates. In ME2 you had what, 12 squadmates to pick from? I had 6 in ME3, and that number dropped to 5 by the end of the game (EDI, Garrus, Kaiden, Liara, James). It was VERY disappointing that I couldn't have my original Wrex/Liara team with me to finish the fight. I mean I get it, Wrex is Krogan royalty at this point in the series, but it still would have been nice.
Other than that, the game was easily the best in the series, and arguably one of the best games ever made overall. The ending did suck the life out of me though. So disappointing.