Valve has a good point about constant updating and instant distribution, but I think this has a downside as well: games will be released prematurely, because the developers "can always fix it later."
I don't like Steam because:
1. I absolutely hate that in order to play a single-player game, it has to launch Steam itself, which then calls home. I bought the darn thing, why do you have to treat me like a pirate? Later, I found out how to turn off Steam doing online verifications, but as far as I can tell, it's all or nothing. You can't choose which games you want to only play single player, and which you want to have as multiplayer. I wonder what happens if you want to play single-player, but you have Steam set to do online verification. Does it just not let you play at all?
2. You can't resell games without selling the whole Steam account. What if I just want to sell one game? Seriously, this is just stupid.
3. I have every single disc I ever bought. While I can understand that others enjoy not having to keep track of discs, I don't have a problem with it. And on my internet connection, downloading an entire game takes a heckuva lot longer than installing from a CD/DVD.
4. Awhile ago, I only had a few minutes to play, so I launched Half-Life 2 Single Player. Then it started downloading a patch automatically. Well, I spent the whole time downloading the blasted patch, which had NO effect on single-player, and I didn't get to play at all that day. How about an option to not download patches automatically?
5. Valve seems pretty solid, but what if they go out of business? If the creditors come knocking, do you really think that Valve will spend money to create and distribute patches to disable the online verification process? I doubt it.
Fix this stuff, and maybe I'll like Steam.