I have just completed it and yes the ending sucks, i wanted to save my fem shep for garrus so i took the best destroy ending, problem with that the geth died, which i hated as i was over the moon when i brought peace between the geth and quarians. Ended up killing them.
While i agree that Mass effect 3's endings are poor, this is not the only big game to suffer from this, in fact from all the games i have played i have yet to play one that had didn't have a ending that was poor and rushed. For example, Fallout 3, Starcraft 2, Doom 3, Borderlands, Quake 4, KotOR 1 and 2, Darksiders 1 and 2, Call of Duty series, Space Marine, Dawn of War 2, Batman Arkham city, Transformers Fall of Cybertron, Gears of War 3, Deadspace 1 and 2.
All those games listed are brillant, fantastic games yet all there endings are pretty bad, anti-climatic or rushed and offer no real closure. So i dunno why ME3 got such stick for it when the vast majority of game endings are pretty poor. Its the same with long running TV series, the final episodes 9 times out of 10 are normally really bad. The only game i have played were the ending was pretty good was realms of the Haunting in 1996 but that game was one of kind.
For me its the journey of the series i find more important than the ending, for example watching Garrus grow over the 3 games i find more rewarding than the end. So in that regard Mass Effect to me is still one of the greatest game series and stories, next to Freespace, starcraft and Deadspace there is.