Yes, Intuos tablets work well with CS3, mine is slightly bigger, but I think I would have done just fine with a 6X9, it does scale up well and too big isn't necessarily better since you need the room on your desk for it.  ;)  Anything you can do with the mouse you can also do with the pen.  I also use it to paint, draw, retouch photos, manips etc and I would have a really hard time going back to a mouse. 

It's not really hard to learn to use, but it does take a little bit of getting used to, not so much learning, just practice really.  I remember when I first got mine I kept going back to the mouse because I was so used to it and the pen felt weird, but then I decided that for a couple of weeks I'd put away the mouse and only use the pen for everything I did, even surfing on the net, that got me used to it, made me much more comfy with it and I hardly ever use the mouse anymore.

Once you get used to it, you'll absolutely love it!  :)

Lucie
finfond.net
finfond.net (store)