The Reapers die.
Sheppard survives.
You can have both Geth and Quarians. (I-M-P-O-R-T-A-N-T)
. . . .
Really, not really THAT bad of an ending, if you can be arsed to get it all done trough the old games + fixing with MP and what not to get the military strength to 5k or what it was.
But really, not the worst ending out there.
My only playtrough was enjoyable and I loved the game itself, but got as everyone else ticked off at the ending.