Major Capcom fighter game coverage site, Shoryuken.com has posted an intensive review of Capcom vs SNK 2, as well as an overview of the full game.
For the complete coverage, check the site's sections.
There's a few details I'd like to add in.
1- While rolls may be slower than CvS1, they are completely invincible in the beginning unlike CvS1. Note that the recovery from rolls differ between characters- Mai would have only 3 frames of lag while Chang has 13 frames, in example. Also, rolls can now be used as a reversal.
2- Short jumps allow for good offence, but if an attack is done during the short jump, a 6 frame lag occurs when landing. Connecting short jump attacks to normal moves on the ground is nowhere as easy as KOF. However, the lag can be canceled by doing specials or supers when landing, allowing easy combos for some of the characters. Also, note that Parry, Just defence and special moves cannot be done during a short jump.
3- Stopping from a run leaves 11 frames of hideous lag. Better to attack, jump or roll instead. . -H.Moriarty