I like Steam in general, but it took awhile. I signed up when it first came out to play Half-Life 2 and it was a completely unstable mess, but they've fixed that. And I was ok with the fact that I had to use it to play a Valve game. Their amazing sales mean that I've played quite a few games I never would have played.
But goddammit, I bought Saints Row the Third retail, and it took Steam a good six fucking hours to download, install, and update it, after I had already installed from the disc. I'd like to think it was a glitch, but I see no reason why I should have to go through Steam and have it do a ridiculously long download to play a game that was bought retail, which I have the damn disc for, and which I have a valid DVD key for. That pissed me off, so I'm all for Steam being a digital store with awesome sales, and I'll accept having to use Steam for Valve games since Steam was created by Valve, but having to use it for third party games bought retail crosses the line. I know it's designed to prevent piracy, but pirates will just bypass all the security and run the game in an offline mode without Steam activation, and it will be far less time consuming than getting it to run when bought in a damn store.
And lastly, games that require both Steam and Games for Windows Live are complete bullshit. There's no reason for it, at all.