Just finished the game, like the rest I'm torn about the ending. I don't know what to think, at one hand I'm not mad they went the "sad" route, but you get such little closure of what actually happened. Could have used another 10 minutes of cut scene material, especially if your going to make such a big decision right at the end.
What sucks even more is the last 2-3 hours of gameplay is tremendously good, then it just goes downhill.
This basically sums up the ending.