I'm just moving down that path after years of using the mouse. While I plan to do photo retouching with the tablet, that was not the deciding factor. It was while I was designing my latest trading pin that I finally had enough and decided there had to be a better way to do graphics. I've chosen the Wacom Intuos and selected the 12x19 size tablet which should work well paired with the 24" wide screen flat panel display I just got. It does take some getting used to as I am not yet comfortable watching the screen instead of the tablet while drawing. It is better than the mouse though. I've always said, drawing with a mouse is like trying to draw with a brick. A pen feels much more comfortable and I like how PhotoShop, CorelDraw, and Painter utilize the pen with various pressure points. The Wacom is pretty good in that it has controls for left-handed artists as well as right-handed.
Jeff