Not often that things do more than they claim, but this does. Ours probably works fine in XP and OS X (other reviews suggest this is so, as claimed by Wacom), but we have not tried other systems yet.
More important to us is that it also 'just works' in Linux - specifically Ubuntu/Xubuntu 9.04, and it works really well. This is (probably) a function of the 2.6.29 kernel in this release.
Our first tablet, so we are far from expert, but a very pleasant surprise. Love the control that we get in GIMP (Gnu Image Manipulation Program) and Inkscape, and it makes a good, relaxed easy-to-control mouse substitute too. We find the 'Small' (A6) pad is plenty big enough for us. Very precise. We are using it for 3D CAD and schematics as well as for illustrations. It has a lovely feel to it in use, very like pen/pencil and paper.
Highly recommended, but well worth checking on the price asked!
If you do not need the buttons and scroll circle on the pad, it is worth considering the Wacom Bamboo One version at a substantial saving, here:Wacom Bamboo One Graphics Tablet
We find it easier to use a left-hand scroll device (on the laptop pad) whilst doing the main cursor movement with the Wacom pen in the right hand.