Well, first instinct is I don't like the specific background choice. Second, the dark orange highlights are a bit weird, and I'd gotten used to the more neutral grey scheme. Layout-wise, I guess it's fine.
Yeah, I'm not entirely certain about the background choice myself. It's easy enough to change - I just don't know what would be better. I was considering trying out making an image with a bunch of different trading cards (shrunk down to like 50% size) tiled. That might be a look a bit crowded, though.
In terms of colors - that's not really something I'm good at. It does, at least, stand out and make things less bland than they were, which is good. It seems to be changable, but I haven't the faintest notion to what to change it to that would be better, other than blue. But I always wind up making everything blue, when I'm in charge of picking colors :P
I think blue would be fine, to kind of match Steam itself... backgrounds, though--since the layout has that semi-transparent look, I would pick something fairly plain, like a space scene or other, if some kind of slide show/rotation isn't possible.