So, we know that Ultimate Marvel vs. Capcom 3's going to have more, well, everything. More backgrounds, more modes, more new characters. But, part of how Capcom's been positioning this update has been to talk about the tweaks and changes that will make UMvC3 a better more ultimate game than its predecessor.
This video by tournament veteran Maximillian walks you through many of the strange ch-ch-changes coming to the crossover competition. So, some characters' X-Factor buff will last for a shorter period of time than others and Team Aerial Combos get changed up, too, among other things. It's all being done in the name of balancing, so it'll be interesting to see how much players will need to adjust to the latest round of fine-tuning.
Assist Me: Breakdown of Gameplay Changes [Capcom Unity]