This thing is tiny. No bigger than a car key and easily fits on your keychain but make no mistake, it illuminates. On its least powerful setting, it's enough light to find what you're looking for on a dark night. On it's highest setting it'll blind an opponent or scare away a nocturnal animal. The case will glow in the dark for some time after you're done using it so if you set it down it'll be easy to find in the dark.
The controls are easy and as small as it is I did not have difficulty finding the power button by feel. The documentation say's its weather resistant but I haven't tested that yet.
One issue I had was attaching the included carabiner. It has a very tight split ring so it took some effort to get it attached [-0.5 star for all the cursing] BUT the carabiner is stiff and makes it convenient to remove from your key ring or gear-loop. I don't know how long the charge will last but it's rechargeable so not a big deal if I have to plug it into my battery bank for an hour. I do know my neighbors [~100m distant] commented on it's brightness with astonishment even though its more of a spot light than a throw light.
This thing will give you 20m of 'daylight' for just a couple of grams of weight, definitely worth the $30. An item you should add to your EDC even if you already have a light.