I hate steam enough that i actually registered on these forums SPECIFICALLY to answer this. Now to be fair i will start this by saying that most of my problems are split between a bad ISP (government mandated monopoly) and Steam feeling it necessary to abuse said internet service.
Now i know steam is ON THE INTERNET, but my problems are with its obsessive need to prove that. I know game patches that fix bugs or add content are good, but when Kings quest or the Doom need to be updated twice in one week somethings wrong. With my bad ISP i have also grown to dread updates because of lost data packets. If a download goes wrong the best case scenario is a complete restart of the download. Worst case is steam no longer authenticating its own DRM software requiring a complete reinstall of steam itself (and any games you forget to back up). Its also something of a kick in the teeth to come home from work to find out you cant play because its in the middle of an update. For a while i stayed in offline mode, but then i cant use any of my online games. After a lengthy time dealing with tech support (including a 1 month wait for a response) the best, and only, advice they had was to turn off my firewall and connect my computer directly into the modem. They recommended it 3 times. I tried it once. It did nothing, well nothing useful. All the DRM software made me do was pirate copies of games i already own, and being someone who is against piracy myself i think they have this backwards.
I am also very skeptical of where this DRM software will go, Ubisoft showed just how crazy they can be with it, Steam is the first example i know of that a game required online authorization and im sure they have no problems going further.