People are comparing cinema 3D with NVIDIA's 3D Vision, and it's really not the same.
I've got a good 3D tv (Samsung 8500), and I've tried a few 3D movies. I agree that it's a gimmick, and not that good.
But playing a game with 3D Vision is a much better experience--for the titles that have support through the publisher or mods. I've played the first 2 Batmans, Dishonored, and Skyrim with 3D Vision, and the 3D was good. For Skyrim if I had to choose, I'd still prefer a good ENB config to 3D, but if you have a beefy enough rig you can use both.
Is it worth the $500 for a good Lightboost monitor? IMO, no, unless you are in need of a new monitor and have money to burn. But the tech is much better than you'd expect if you haven't tried it, and it definitely improves some games, though not enough to be worth the cost.