The developers absolutely deserve to be applauded for their work, but declaring it as "simply beautiful" is almost laughable. I think that it's actually quite ugly. And even if you disagree, I don't think it's fair to call your own work beautiful unless you've proven that the overwhelming majority consistently enjoys your aesthetic.
Artistic quality is one of those things that defy definition. It may be that it's aesthetically pleasing, or it may be that its design communicate some other inner quality or a completely different idea. It may be that the inner quality, in itself, has some aesthetic quality, much like a beautiful mathematical proof.
I read that as more of a goal statement than a description. Whether or not you think they've succeeded, they certainly seem to have put a lot of effort towards that goal: http://live.gnome.org/GnomeShell/Design/
