I've got one of those at the moment, and have had it for a few years. It's good if you don't like to wave your arm all over the place while working (meaning, if you have limited desktop space, that's a plus). I definitely recommend getting one to try out.
A few notes, though: you might want to look into extra pens if you use the pen a lot (although they aren't terribly cheap, at about $30 apiece). I'm on my third in about two or three years, if I'm not mistaken- and I *should* be getting another, due to the condition of the current one. The first stopped working out of the blue, the second just disappeared, I think, and this third one's rubber grip is eroding away, its body cracked on me, and the grip is misshapen in the shape of finger indentations from heavy use. Wear and tear! =)
If a mouse is coming with that one on ebay, keep in mind that it only works on the active area- which means lots of picking up the mouse and re-centering it. That was something to adapt to when I first got mine. Also, the felt on the bottom picks up LOTS of junk- you have to scrape it off with all the lint somewhat often or mouse movement gets quite slow.
I would recommend looking around for refurbs- a quick google search brought up a couple at $40.
http://www.google.com/products...roup&resnum=1&ct=title