X-Men is a fun game... on ameatur difficulty level.  When I cranked it up to Hero (since you can't get any farther than the third level on ameatur), I found it almost impossible to do anything.  I got tired of playing the levels all over again, fighting the same, almost randomly apearing enemies coming from doors at any moment and surrounding me.  Although the game may have captured the feel of the X-Men, I didn't think they did a good job with the actual game aspect, which is probably the most important thing.  If you want to play a good Marvel game, try Marvel Super-heroes: war of the Gems.  It is much more balanced and fun than Sega's attempt at making an X-men game.