I've been playing around with it for a week and I really like it so far, enough to transition everything over from Basecamp.

I really like that I'll be able to incorporate the development progress easily into an internal status page for our startup. (Actually thinking of doing a road-based metaphor visualization of the 'interstates'.)

I'm very hesitant to have a publicly visible progress page though, out of concern that would encourage people to wait to pay until a certain announced feature was in place. Would at least have to be handled carefully.