I have previously used a Wacom Graphire (precursor to the current Bamboo) and a Wacom Intuos3 (A6). Currently I use a Wacom Intuos4 Medium.
I like them all. The Medium size tablet is not necessarily better than the A6 Intuos3 one, I think. Intuos4 looks prettier but I don't really notice the higher resolution of Intuos4 compared to Intuos3. Possibly one might spare the wrist somewhat with the larger area, but the precision is not affected in my view.
Anyway, here's my little summary of the latest tablet:
viewtopic.php?f=15&t=3000.
Griatch