I've installed the latest Mageia 3 beta with Gnome 3 and played with it a little in the past few days.
Although I like the overall impression, there is an (almost) showstopper for me, namely the fact that the wireless network (ath9k) doesn't work right from the start as in Mageia 2. I filed this as bug 8758.
Working with Gnome3, I found that some gvfs back-ends weren't set up correctly so that the file chooser couldn't access smb or ssh locations. I had to install gvfs-smb manually as well as the openssh client. This is an inconvenience but I'm not sure it can be categorized as a bug.
I've had two occassions of X crashing as well. This is filed as bug 8877.
regards,
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Reinout van Schouwen