I finished it (Mass Effect 3). The controversy over the ending forced it upon me, since I was feeling less and less qualified to discuss the game as more and more people were having discussions about it in which I couldn't participate. I vow to return to my variegated playthroughs, but for the information of anyone who was following those posts, I finished on Perfect Paragon, but had to cut corners to reach the end, which is in itself a very interesting opportunity for future analysis.
The ending is in my opinion of mixed quality, and my guess is that it's the quality problems that have driven much of the player-protest. The true difficulty is in my opinion that so much of Mass Effect is so good, so far beyond anything we've played before, that the bits that are run-of-the-mill RPG fare and run-of-the-mill sci-fi fare really hurt.
Ending this thing in a way that lives up to the heights to which Mass Effect has soared, especially on the very first try and in the development situation in which the Mass Effect 3 team must have found themselves, was almost certainly an impossible task. Thank goodness they're getting another shot. There are things they won't be able to fix, of course, like the sheer number of times you're told that "This is it," which eventually made me feel like some terrible Reaper-writer was shooting a red ray of exposition into my skull. But I can certainly see how some new cinematics would make a big difference.
The quality issue is obscuring, however, more interesting problems of choice and irrevocability. To those I shall return.
