I use TrackIR with FS2004 and VFR scenery and very good it is too.
My version came with a clip with three small reflective strips which attaches to a baseball cap.
With a very small movement of the head and your eyes still looking straight ahead at the screen, the field of view changes as you would expect with the corresponding head movement. Actual head movement is amplified to result in an greater 'apparent' movement on screen.
I found TrackIR made flying circuits much easier as you can quickly look around for your visual references almost as you would for real. Approaches and flares improved too. If you have airport scenery then even better as taxiing is much easier.
I found the whole Flight Sim experience hugely beneficial when I was training for the PPL, especialy the nav work. When I then went on to my IMCR my club wanted to me use a ropey old simulator for an not inconsiderable amount of money per hour. My FS set-up at home was significantly better, I could practice instrument procedures all day, and the end result was I found flying the approaches for real much less stressful as I'd done them so many times on the sim.