As much as Steam pisses me off sometimes (trying to get into offline mode pissed me off recently), I'm willing to look past most of it because of how cheap a lot of their games are. I would prefer another medium, but most of their deals are hard to beat.
I've luckily ain't had much issues w/ Steam. Just once, during the free weekend for Killing Floor and pre-loading for Borderlands was going on and everybody was downloading, I couldn't access my games for over like 20-30 mins. But, I did the BLOB file reset trick (rename BLOB file to something else; let Steam re-create the BLOB file) and it worked from then on.
Of course, anytime Steam's down for maintenance - well, that part sucks...
I luckily never had a problem for Offline Mode. I consider myself lucky, given how many have rightfully so complained about this issue.
But, I do agree on their pricing - Steam's prices are often very cheap on their sales. When their games are often the price of console game rentals at Hollywood Video ($6.00 or less), hard for me to say "no" to Steam.
I prefer GOG over Steam b/c of the NO DRM policy. So, if a game is on both Steam and GOG, unless the price difference is really a major difference (and it usually isn't), I normally go w/ GOG.
When I consider the fact that a few games I've gotten off Steam have never so much as actually worked or even installed correctly, I tend to consider that any deal is probably a bad one. To this day I still can't play Killing Floor.
To get Killing Floor going, if I recall - I had to turn off all anti-virus, firewall, and mal-ware killer programs that like to run in the background - i.e. Ad-aware, Avira, and Online Armor.
Hopefully, it's as simple as that.
But given
this thread and
these boards littered w/ booting-up and loading issues, it probably isn't...