Quesada has handed over the title of EiC to Axel Alonso, who was editing the X-Books and Max titles. Quesada himself is moving into a higher creative position, overseeing Marvel's multi-media products- games, movies, and the like. Alonso will be handling the comics themselves.
I wouldn't expect too much of a change. Honestly, I think this is good for Quesada, as his role was expanding due to Marvel's ever-growing cinematic presence.
While I'm not happy with the X-Titles these days, that's mostly due to fatigue on my end. Alonso seems to be a pretty good editor and I'm curious to see where the MU goes from here.