I'm still on version 6. I absolutely love the program. Despit my initial hopes, Motion doesn't even come close to holding a candle to it.
I'd say the learning curve is pretty steep...steeper than a nonlinear editor. But the key is to not think of it as an editing program -- the interface is only vaguely similar, but still, that was my main hangup when I was learning the software. You really just have to think of it as Photoshop on a temporal plane, so if you're familiar with Photoshop, you should have a fine old time. But I'd get a book anyway, just so you can pick up some shortcuts....there are so many little tricks to the program that I'd never have figured out on my own. And some of the features, like Time Remapping, are really confusing, so it's helpful to have someone explain them.
This is one program where having two monitors would really come in handy, though. Especially when you start working with comps of upwards of 100 layers.