The new C9 works very well for me, it is MUCH faster now and its functionalities are nice. Sadly, its new design is just horrible. I am disappointed that Microsoft can't come up with a nicer design.
These colors are just absolutely awful! I can not visit this site more than 5-10 minutes before I get sick of the colors and my eyes hurt.
Atleast bring some kind of themes... that would do just fine. ( ...and no, I do not want to theme this thing myself by custom CSS and junk. I don't have time for that, just allow me to click and choose themes... 10 themes would do! )
My two cents.
EDIT : Or maybe it's the white background... hurts my eyes. Some kind of light gray would atleast help a lot.