"XMen: Last Stand" was ok, but nothing special. It took an awfully long time to get going. By 30 minutes in, I was waiting for the ending which - while it was entertaining - went down pretty much the way I expected it to. It also felt choppy at times, as if large pieces of characterization had been left on the cutting room floor. It's a decent enough "popcorn" movie, but don't go expecting to be awed.
One thing I will say - stay in the theater all the way to the end of the credits. There's a scene that's shown then, and if you get up as the credits roll - no final tidbit for you :)