I've used Wacom tablets before and was impressed. Specifically, the pressure sensitivity is far more accurate than I expected and I loved the ease of use of having an eraser end of the pen so you can just turn it over and correct your mistakes just like a proper pencil - very intuitive!
Recently I've been too busy buying other gadgets to get a tablet but it's on my wishlist (together with a Mac Pro, decent monitor, calibrator, etc, etc)...
