It works exactly like a pencil. You press down on the pad, it draws. You lift off the pad, it doesn't. If you hover the pen slightly over it (About an inch or less), it moves the cursor without drawing.
There are two sides, just like a pencil. One is the drawing tip, and one is the eraser. Both work as you would expect them to. (The harder you press, the harder it draws/erases. That is, if your program supports it. Wacom usually ships a Painter Classic which does support this. Photoshop does support it also, and I think Gimp also. There are plenty more, I'm sure.)
There is also 2 buttons on the pen, but they are just as an added feature. You can set them to do any keyboard command (I use one to do CTRL+Z, and the other to Right Click, since the eraser does NOT act as a right clicker), or pop a menu up, or do nothing. They are VERY easy to press, probably easier than the buttons on a worn out controller. It's a rock-back switch kind of 2-button thing. It looks like this:
|><|
Pushing down on the one wedge sticking up is button 1, pushing down on the other wedge is button 2. It's really easy, and you don't really need them. I rarely use them except in AutoCAD.
Anyway, I recommend you get the Graphire3 6x8 (The 4x5 is just too small, at least for me.). It's really nice, and I am in love with it.
And as long as you can use a pencil, you can use this thing. Also, it comes with a mouse that works on the board too. It's a 2 button mouse with a mouse wheel. Feels like any old mouse, but only works on the tablet.
And one final thing (lol): A lot of people ask this. THERE ARE NO BATTERIES. Not in the pen, not in the mouse. No wires either. I think it runs by magnet (although I am not entirely sure.). The only thing that gets any juice is the board itself.