Just installed the tracks on the top of my '08 FJ, and they absolutely rock. Totally low-profile rack solution, keeps the additional height of adding a rack to the absolute minimum. Interesting to note that the Yak tracks are identical to the Thule racks - once they're installed, you can install either brand's towers.
I'd echo everything erich mentions, with a few caveats, the most significant being the "vehicle-specific mounting guide" provided by Yakima. I was surprised to learn (and I'm generalizing here) that, unless installing the tracks on a pre-2001 vehicle, you're very likely NOT to have specific instructions for your truck/car. So your install's probably going to require a slight bit of winging it, which might make some nervous, considering you're drilling directly into the roof of your ride. Certainly made me jittery. If you can chat with a professional installer (like the Rack Attack guys), do so - you'll feel a bit better about doing it yourself. You should also know that Bondo sells a patch/repair kit, probably available at your local auto parts store for ten bucks.
Otherwise the install directions are crystal-clear, and it's actually a very simple process once you get the first one or two figured out. And the end product is absolutely rock-solid. Highly recommended - but Yak REALLY needs to update the vehicle guide (or at least put it on the web!).