The webfont used (Cantarell) does not look good in Windows. The texts are almost unreadable:
http://op111.net/u/misc/20110407-win7-fx4-gnome.org.png — (It looks fine on Linux.)
Cantarell, by the way, is also the UI font of Gnome Shell. Not a bad UI font, I think, but it has a narrow glyph range (about 400) and only includes Latin.
Moving to the larger picture, my impression from the Gnome Shell desktop up to now is that it is an interesting experiment, trying to rethink as it does a lot of stuff that we have grown to take for granted in desktop environments. But it is not necessarily a good desktop experience. Up to now (I have used it for about 40 hours in total) I find it tiring and distracting, rather than distraction-free. Switching between app windows, e.g., is not a pleasant experience for me, with all the action I see on the screen and that I have to take myself each time I want to switch. (Alt-tabbing avoids all that, but I don’t always switch windows with Alt+Tab.) Another thing that does not help me, and that I find strange as an design decision, is the position of the clock right in the middle of the topbar. It causes me stress; I feel like time is hunting me.
In general, Gnome Shell seems to me to offer an experience more tuned to small rather than large screens. In a 2560*1600 screen, say, and if you prefer using the mouse rather than the keyboard, the distances you have to travel are ridiculous.
I expect the whole thing to improve in the next couple of years or so, but I am curious to see how much it can improve given its basic design principles.