I'm usually someone who's a fairly early adopter, but because I make sites for clients and not for fun, I have to wait until things are fairly stable to begin putting my clients on something new.
I have zero faith in Drupal to be finished "on time" since there is no release date. Drupal 7 has been coming out in "two weeks" for like a year now. I'm fine with this to a certain point, but I'm going to wait until they finish bike shedding and put something out that's "good enough" before I start working with it.
Every version of Drupal 7 I've installed to date and played around with, hasn't left me with much confidence to start building sites with it. Contrib is even worse. I'm waiting for RC1 to give it another run.