Here's the interesting thing about Offline mode, it's always been my main peeve about Steam because the idea of being locked out of my games because of a blip in the internet pisses me right off. I replaced my computer this month and never tested Offline mode until now, and it works! I can kill my connection with or without Steam running, then choose the "Start in Offline mode" option and play anything. Even Source games. On my old computer I get the typical must-be-online-to-go-offline bullshit.
Apparently Offline mode is some kind of a lottery, and I won this time.
I tried to avoid Steam but needed it for the Orange Box a year ago. My library just got big enough to need a scroll bar yesterday. I passionately hate DRM but I'm willing to meet Steam halfway for the convenience, not to mention the sales. I don't even care if you can get the same games cheaper elsewhere, this is absolute pocket change.
Still have to complain about the store UI, and how the client doesn't have tabbed browsing, so if I want to buy multiple things off the list of specials I have to scroll back through the whole list after adding each one.
