I just downloaded the new client for Windows Live 3.0 to check it out and it looks very familiar. It's basically just a slimmed down version of the Zune software but for games instead of music, obviously. Here's a few screenshots I took for comparison purposes:
 

There isn't much there when compared to things such as Steam of even the Zune software. Hopefully Microsoft will be adding features in the near future. I personally was expecting some more community oriented features but it appears you can't even view friends in this client. 1/5 stars, but an A for effort. At least Microsoft is trying to get with the PC game times.
 
 
 
 
*edit: I am trying to get the hang of the picture posting system, not going too well. Sorry for the ugly layout.*