Deb, I definately thought Xmen2 was better than the first one. Because we already know the characters from the first one, there was no 'time-wasting' whilst introducing them all - the film's story is stand-alone, but the characters aren't - so it helps if you've seen the first.
Plenty of action, plenty of effects, storyline's ok - if you enjoyed the first, you'll love the second I think