I have a track IR3 (not pro) at home, i got it about 2 months ago. I would say that this review is pretty accurate.

The device takes some getting used to, but then its pretty damn sweet. In short, its a head tracking system. Its relatively inexpensive *around $150* and it has a couple modes of operation. Nicely , one of them is mouse emulation. This means you can get head tracking pretty much instantly into any game you play. Not so useful in an RTS, but put it into any FPS or Sim, and you’re rockin.

For my own setup: I mounted my reflective dot on the mic of my headset. This turns out to be a convenient place for head tracking. Even better, when I’m extra lazy, I can just use my head to move my mouse around. Awesome

Any way.. The people getting paid at Ars Technica can write up a much better review than I can.. so go check it out.