I like some of the changes, and am generally fine with them. Tiny details are annoying (cutting Jean Grey's hair, and Juggernaut's lame, lame, lame costume.) It's weird, becuase I adore the title Ultimates (which is the Avengers.) Whereas I am just OK with the X-Men version. I think it's because I grew up reading the X-men faithfully, and not the Avengers.
But, parts are still awesome. The characters are handled pretty well (except for Professor X, randomly,) I am enjoying the relationship between the Brotherhood and Xavier's School. Even if I do have to take things like Nightcrawler and Rogue being part of Weapon X to get there.
Oh, and I really don't like the character of Wraith. He's a pain, but worse, he's unrealistic.