If was awful, almost as bad as SFIV's netcode. No idea why I bought the PS4 version of MvC3 and I'm so glad MvCi is using SFV's rollback netcode. I just hope they improve the one-sided rollback some people have on these poor connections.
The MvC3 netcode on PS3/360 was KoFXIII quality. SFIV netcode was WAY better than that.