Normally when you hit the volume down key all the way, it goes to silent, and then one more press it will go to vibrate mode. I have noticed it doesn't do this with MUIU.
I'm not sure if this is a bug or this is just how MUIU was made but it can be a pain to get into vibrate mode now.
I had trouble with downloading from the market last night when I installed MUIU, but I think all I did was reboot and now it's working fine. Haven't tested WiFi though.
As far as syncing facebook to your contact pictures, I thought that was a feature with sense? I could be wrong but I didn't...