I find that, for the most part, the best Steam offers is extra hoops to jump through, and less access to the game content I bought and own.
I am, realistically, a pc gamer through and through, but Steam enrages me.
I prefer physical copies in the first place, and just cannot see the apparent shining appeal of having to have access to an internet connection to use the games that, by rights, I should be able to play without all the hassle.
An added element of this is that I don't play online games with people I don't know, so I find virtually no use for Steam beyond a chat system to speak with my friends.
Nigh all the games I possess on Steam are single-player, and those few that have I multi-play I only play with friends.
Not to mention that, to access a Steam game, Steam needs to be open, and running the whole time.
Personally, I don't see the point, and miss the tried-and-true CD Key system.
Essentially, Steam is a waste of time. There. I said it.
IF you want to play online shooters like TF2, I see no reason that you can't join a server yourself, like the old days, without 'online stores' like Steam holding your hand.