SPOILERS!!!! SPOILERS!!!!
I went to what I'm pretty sure was the FIRST screening of this and unless they did some radical tests, the ending is virtually intact. There are some changes, but not much. The Only major thing was the loss of tension at the last fight because originally they went in and Cage tells them to "Not shot an Alpha!" well of course someone does and it resets the day again, but this time, the Mimics KNOW they're coming and when they came in the first time, there was maybe a handful of enemies, but then you see HUNDREDS come in and hide, waiting for them to return, which is what you see on screen now. The problem I had with it, was that you knew the enemy was waiting and prepared, that stacked the odds against the heroes, but now it seems like a repeat of the beach slaughter again.
ART - they actually trimmed a bit from the last scene and made it seem a little LESS happy ending then the original. In the first version, cage comes up to Rita and she says nothing, she just smiles as if she remembers everything they went thru. I half expected a kiss there.