First off, I would like to say that I do like the new design. The only problem I have with the design in some cases is the use of web fonts. While it's not necessarily a WordPress problem, there is a good chance that Chrome users on Windows 7 (and maybe 8?) machines will hard time reading text due to an on going issue with Chrome and font smoothing.
I'm having trouble on my when I load up my WordPress site on my Windows 7 machine (which is my main), however, I'm not having the problem on my Windows 8 machine.
The above are screens from my Windows 7 machine. As you can see the fonts look terrible, and depending on the words and the size they can be very difficult to read. I'm not exactly sure what wordpress can do about this, but perhaps using a standard font for the admin dash would be helpful.