I know it seems in bad taste to piss on Steam after so many great deals, but all the same:
the steam app is a pile of shit. no other app on my computer runs as poorly as it does. it takes forever to load up, the IE interface for the store and community are often slow and often don't work correctly, and the download management is archaic. I'm really hoping Battle.net 2.0 comes along and kicks Valve's ass into gear on this. granted, they do update this interface very often, which is appreciated, and is also the reason they haven't changed it, I'd guess, but all the same, it's 2010; time for a proper update!