The issue I have with Steam is less about "Steam" and more about the behind-the-scenes stuff, that gamers don't get to see.
For example, Steamworks bundles the Steam Store Client with all Steamwork enabled games. Even for retail purchases.
This means that everyone who purchased Deus Ex: Human Revolution, Call of Duty: Modern Warfare 3, The Elder Scrolls V: Skyrim, Civilization V, etc., on the PC are now Valve customers whether they wanted to be or not.
Valve trumpets it's 30,000,000 accounts like kind of achievement. I ask: how many of those accounts were forced to be made so someone could actually use the game they just paid honest money for?
Another issue is that Steam makes all games Online Only. It's Offline mode simply doesn't work unless you can connect to the internet first.
The logical falacy of that is mind numbing: if I could connect to the internet, why would I need an offline mode?
The last issue is of course the impending Steam monopoly: thanks to Steamworks, all other Digital Distribution serices are essentially Steam Re-sellers, doing little more than selling Steam Serial Numbers.
The problem is that all Steamwork games launch the Steam Store Client first: if I buy a Steamworks game on Impulse, it launches Steam, forces me to make a Steam Account, and downloads my game from there.
Steam, in the current business climate, have to be nice to their customers to retain them. As everyone apart from GOG.com now sells Steamworks games, that "be nice" phase is coming to an end.
For example, Valve pulled several EA titles from Steam because they were selling DLC in-game. This meant that Valve couldn't take their 30% cut, and so decided to fuck it's customers and pull those games and all support for it.
Another solid example is that Valve have enforced the Terms of Service upon Bethesda Softworks when it was discovered Skyrim was capable of running without Steam launching first - a direct violation of the Terms of Service for Steamworks.
Bethesda were forced to patch their game, and screw their customers who needed to modify the game in order for it to run, otherwise Valve would pull the game from Steam. Because the game was Steamworks enabled, this meant customers who purchased the game in stores would be unable to even install their legally purchased games.
Valve are making their move. It won't be long before Valve are as hated as Activision - but by then, it'll be too late: they'll have all your games.