Hi Russ,
I've got one, and have used it for quite a long time now, in lots of simulation games, like Falcon 4, MSFS, IL2, LOMAC, LFS, Richard Burns Rally and of course SS08, to name a handfull. And I don't ever want to do without it again.
It's really easy to get used to. It's a bit awkward at first, and you feel you really have to "guide" the view towards the things you want to see. So you have to stick with it a bit and learn how the movement of your actual head is amplified in the game. All of this is of course also customizable with the TIR software, so it's a bit of fiddling around to find the proper setup for you. But it's really straight forward stuff.
And then after a week or so, you just instincively put your "eyes" on target and it gets second nature, so much that you don't even think about it at all any more. And it will make everything so much more immersive, I would recommend it to anyone that has a bit of cash to invest in their gaming rig.
It can be setup to be really sensitive, but I haven't really found it annoying at all when it moves when you're not sitting still. In fact, it will make you sit still more...
Oops, I sound like a salesman.. well, I just really like it, let's keep it at that.
Regards,
Fred