I have used Steam since it was first released and have no real problems with it anymore. It was annoying when the friends server was down for like...a year and I'm still bothered that it frequently chooses not to save my server filters but that's just cosmetic and not enough for me to hate it. I am someone who loves to have hard copies of all my games and have only purchased Valve games on Steam, however, they work perfectly with it and other than a short bout with being unable to play them while offline I have no complaints.
As a person who played CS in the WON days I love the crap out of not having to use xfire, gametiger or any of the bajillion other methods for finding servers so I'm predisposed to like it. If I want to play Half-Life again I don't have to go rooting through my disc collection I just right click on it and tell it to install, I don't have to go trudging through the many tubes to find updates for my games anymore, and it stays comfortably within it's own realm of influence (or at least that's what my firewall tells me, they could be colluding).