I've just completed Mass Effect 3 in a total of 28 hours. I think on the whole, it's generally a good game, though, with time to reflect, I'm sure I'll see it as a bit shit.
Most of the time I was playing involved:
Walking around the Citadel, not knowing where the hell I was going.
Scanning Planets and Systems in the hopes I'll find something useful.
Hiding in cover waiting for my shields to recharge.
Hiding in cover waiting for the enemies to poke their heads out.
Getting killed by insta-kill moves and things you have no time to react to.
Killing enemies that are completely boring cannon fodder.
The endings were also so horrible because it didn't matter what you did during any of the games because the choices are the same no matter how you went about it. A B or C. Take your pick. Literally 90% of the ending cutscenes are the same. It's stupid. As a game that prides itself on user decision affecting gameplay, this was really unforgivable.