I have a wacom bamboo tablet. One of more economical models and I love it. Some tasks cannot be replaced by a mouse however I do find for graphic design and some editing of my photos it is useful. The most useful diffarence is the pressure sensitivity , also selecting points is more intuitive with a pen.The only disadvantage I've had is that extened use gives my wrist some strain but thats probably because I dont use it enough

_________________
EOS 400D+BG-E3 Grip --- EF-S 18-55mm f/3.5-5.6 --- EF-S 15-85mm f/3.5-5.6 IS USM --- EF-S 50mm f/1.8 --- Zeikos 0.40x fisheye adapter
My Flickr 