I bought this light as a simple and lightweight headlamp for ultralight backpacking.
The Good: It is light, simple to operate, decent runtime, good beam angle at 35°, and brightness levels. It is fairly comfortable to wear, does not shine any light back into the wearer's eyes or onto their nose.
The Bad: Skinny headband makes the headlamp a little too easy to flip up or down, it is not waterproof, though it held up to some rain just fine. The runtimes are completely false and ridiculous. It draws 190 mA on one led, 400 mA on two, and 680 mA on three. It should run 14-16 hours maximum on low with an Alkaline battery.
Things I would change: O-ring everything. Make the lowest setting lower, as it is way more light than needed to look into a backpack or read in a tent. Make the headband ¼" or so wider.
Overall, this light is quite good for the money. It is plenty bright for most uses, is lightweight and simple to operate, and does not shine in my eyes when I am wearing it. My only real knock against it is that the runtimes are completely false. This is a regulated light, so it will stay at almost full brightness until it will rapidly dim when the battery is dead. I am going to use this light as a backup, as it is very small and compact, but does not compete with more expensive lamps in the departments of: build quality, waterproofness, brightness, secureness on head, or runtime.
For the price, I don't think you can do better if you need a simple and very lightweight AA headlamp. If you need more light or runtime without spending much more money, I recommend the Icon Irix 2. Unfortunately, it comes with its own list of shortcomings. It wil not stay in the headband, and it glares in your eyes.
It seems like headlamp manufacturers never test their gear, or consider even though most obvious fixes to major issues. Until I find a headlamp that actually does what most users want, I will stick with my Fenix H20. It is twice the price of the others I discussed, but such a superior headlamp if you have the cash. If you want something other than a single AA headlamp, there are plenty of choices, but they will all be heavier and bulkier than the AA lights (excluding cr2032-powered headlamps