It's always a bit hard to jugde a plugin, which is free. But this one is really an ugly nightmare. I installed it to add an avatar upload thorugh registration, but this feature is broken. So I deinstalled Cimy User Extra Fields and coded it by hand.
Unfortunately their are a lot of database-entries and folders left, after uninstalling.
I would recommend everybody to use Register redux, pie register or code it by hand (which is not that much to do).