Just beat ME3. What a great game. The ending was a bit disappointing and I can't imagine what those who saw it first without the Extended Cut felt. From what I read it was pretty abysmal. That didn't detract from the experience much, though. The entire game was about tying up loose ends and saying goodbye, and it's hard to put an exclamation point on it in the final scenes.
My main gripe was
(SPOILER)the three choices at the end didn't make any sense. The whole game centered around the theme that the universe isn't black or white. Yet the final choice was exactly that: Destroy the Reapers and all other synthetic life, let them all live, or combine them all into one 'super race' (that makes no sense). I wanted to destroy them from the beginning, yet I also spent a lot of time in the game driving the point home that the Geth and EDI are different from the Reapers. That was the whole point in the game. Reapers=bad sure, but not all synthetics are bad. I was disappointed that my choices from before didn't matter in the end and I ended up destroying them all, because the other two choices (Shephard controls Reapers, or the ludicrous synthesis option) really made no sense in the context of the game. I would have liked to see my previous choices in the game affect the final choice in the end rather than it just be based on the readiness score.
Second gripe:
(SPOILER)There was no final boss. Just a final wave of enemies (which was pretty crazy). RPGs are always at their best when there is a 'big bad' to fight and I was really hoping to go up against Harbinger at the end. But there was nothing. Not even a final fight with the Illusive Man.