I have used it - I used it for a couple of months - at least a year ago, if not more. I actually liked it; but then I decided that I wasn't engaging enough with my "stuff" because I could just whack it into a system online almost [I]too[I] quickly...

But from what I remember, it was pretty intuitive, and I never had any issues with it syncing on my iPhone. It had enough functionality (and some good video tutorials) that you could go as "vanilla" or as customised as you'd want. But I've never used OmniFocus or any of the high-powered, fee-based electronic list managers, so your mileage may vary!