Ok i have one.
It works by tracking your head movement, but you can adjust your sensitivity so that 10 degrees head movement either way will give you full look around ability, up down and side to side.
You do not even notice your moving your head after a while as its a totally natural movement anyway.
You just keep your eyes on the screen and move head slightly to track enemy or look around.
In IL2 FB with dedicated support it is the only way to play, its that good.
However in AH i do not use it and doubt many do.
For the following reasons.
You have to map mouse look in AH which works fine and is smooth panning etc.
However because AH does not have dedicated support for it you have to play using the mouse emulation mode which uses the mouse look view mode in AH.
Now we come to the problem with AH, even though the AH mouse look is smooth panning unfortunately when using the TrackIR it does not pan smoothly it jerks or it might be more precise to say the view moves in small steps. No matter how big or even small a view movement you require it will not pan smoothly.
You will also need to map a dead zone to the mouse view horizontal and vertical movements, as nothing is more offputting as the smallest head movement causing your view to move around even a small amount just as your saddling up a con.
Another big disadvantage in AH is you are stuck with the default head positions, you cannot have default preferred head positions set like you can using hat views.
Now if AH does get dedicated support it truely would be awesome if you could also have the head postion sway side to side to improve your view as your head naturally would, but that may be hoping for too much even if it was technically possible.
You should also keep in mind that i cannot recall any member of HTC ever saying that they will provide dedicated support for TrackIR.
However if they tried it in IL2FB they would want it (I hope)
So currently its crap in AH and works great in IL2FB.
Problem is as good as IL2FB is i hate the damn game. If you go to play online you can wait for 30 mins or more while they wait for enuf players, or find the vast majority of games have ridiculous easy mode FM or view settings enabled.
Or my pet hate no icon for your own plane on the map and nothing to give you the slightest hint where if any fight is actually taking part.
So you probably guessed by now that i bought this TrackIR and yup its gathering dust on the shelf.