I've tried pretty much all of 'em, FaceTraknoIR, SC's built in face tracker, a TrackIR both with the hat reflectors and IR leds, and now the Tobii. And in the end, I wish I'd never wasted time or money on anything else; the the Tobii just works, perfectly. No issues with lighting, windows, wearing glasses, putting shit on my head, etc. I just hit the hot key to turn it on when I want it, and off when I don't. It is, in a word, amazeballz. Now I don't want to discourage anyone from trying out the free options to see if you like the functionality in general. But if you do, and decide it's something you want to use regularly, and have any glitchy issues that disrupt your experience, then I'd suggest waiting for a sale and springing for the Tobii, as it Just. Plain. Works! Best way I can describe it was sorta like putting on an Oculus for the first time after I'd "played some VR" by slipping a Samsung phone into those goofy face clamps. . .