Let's gather up the facts, shall we? Steam is a form of DRM, if you're banned (VAC or not), you lose your games. Anyone saying "You can buy a hard copy", when I bought Killing Floor, I had to register it with Steam. Same with Red Faction: Guerrilla. And that's not even a Valve/Steam game. It makes you register some games even if you don't have Steam on your computer, which is what happened with my very first Steam-related game, The Ship.
Steam has some great deals, with the Valve Complete Pack which is about $200 normally, going for about $60-$70 during the Steam Christmas sale. Fucking great deals during sales. Plus, some of the games (See: Dwarfs?!, Eufloria, Beat Hazard, G-Mod, Limbo, Monday Night Combat, Magicka, etc.) aren't available in stores or on consoles (As hard copies, but at least on consoles you can keep them if the respective network goes down).
The Steam offline only works if you go offline when you still have internet, otherwise it says "Cannot connect to Steam" or, in reality, "Fuck off, I despise you." People have mixed emotions about Steam because of the way it treats them.
Plus, if you only play single-player games, then you may as well get a console and do your single-player gaming on there, because Steam gives the overlay which lets you track achievements, view videos, and talk to friends. Plus, unlike other distributors, Steam tracks who's completed what achievements and updates your games quickly, for free. You also get the latest news about any game in your library when you select it, as well as which friends are playing it.
Again, the evil comes from the fact that Steam can just disconnect and go offline at times, so you can just lose connection to your friends. If you'll notice, for someone who uses Steam alot, there's more pros than cons. I can't think of much else that's bad about Steam besides the offline, it's DRM, you can lose your games if you're banned for no reason, and some games are over-priced.