User Review: Princeton Tec Quad
It's all the good things that others have said but I love the way you change the batteries. No trying to pry or snap the case open and risk breaking something, like I did on my Aurora headlamp.
There's a small screw that holds the front and back cases halves together. Unscrew it, using the small plastic piece that's part of the head band, and the back half of the case folds down on real hinges. And you don't have to worry about loosing the screw as it's captured in the rear case half, and can't fall out.
All in all I believe this is the best headlamp I've ever had. I bought mine for use while backpacking but wind up using it around the house all the time too.