So far I've heard she's not quite as godly as she was in MvC2, but still very good. One change that I saw listed by people who played her was that her Whirlwind has a long startup now, whether or not you charge it. But right now it's hard to say because the last 10 or so characters they've revealed haven't been available in any of the public tests so players haven't worked out all the details.
Lilarcor's forum posts
Viper looks really good. She's really fast and can 8-way air dash, the EX Thunder Knuckle can travel through projectiles and her Level 3 does crazy good damage. Storm will probably still be great, although she's a little less exciting just because she was one of the uber-tier characters in MvC2. I like the new look of her supers though.
@JJOR64: Strider was recently deconfirmed by Niitsuma and the Capcom side of that list doesn't have Jill. I always thought that list was fake all along, for one simple reason: if that scanned roster really came from Capcom, why would they be missing their own art assets for the unannounced characters?
Like you said, there's no Mega Man on this list and Niitsuma heavily implied that there would be some version of Mega Man in the game, and he also seemed to say there were no more Darkstalkers characters beyond Felicia and Morrigan. On top of that, there's no Frank West, which is weird since he was a silhouette in the very first trailer for the game and was already in TvC.
It definitely looks more legit than just about any other 'leaked' list, but I'm not 100% sure it's real yet.
There are no more Darkstalkers characters besides Felicia and Morrigan, no Sengoku Basara characters, and no Monster Hunter characters. Niitsuma also said there won't be shapeshifting characters because the memory restraints on polygons vs. sprites is much much harder to work around, so Shuma-Gorath and Venom are also almost certainly deconfirmed.