The Fenix E01 is so small and light that you are likely to keep it handy, which makes it more useful than the flashlight you left home. Mine weighed in at approx. 0.95 oz. with the battery installed. The body diameter is about the same as an AA battery (it takes one AAA battery), but about 1/3 longer. It would easily be at home on a keychain if you like keychains with extra things hanging off them. It also will quite comfortably fit in a pocket.

Of course, it's a natural for a purse or fanny pack. Another reviewer commented that the reflector collected lint, which I didn't understand until I got the light. There is no lens covering the reflector. Therefore, if the flashlight is knocking around in a purse, I could see how the reflector could end up collecting lint. On the other hand, there is no lens to crack or get scratched up.

The light turns on and off with a twist of the ring surrounding the reflector. There's no button to push. There is no high or low beam. It's simply on or off.

Given some of the earlier reviews, I expected this light to be brighter than it is. I tested the light on an unlit staircase at night and found that all seven stairs to the landing were well illuminated. The corona around the hotspot covered the entire width of the steps. Going outside, I found the light to be adequate for illuminating a path while walking outside at night, but don't expect it to "throw" its beam any significant distance. There is a hotspot in the center of the beam, but more even and wider than the hotspot from an incandescent mini-MagLite. The hotspot has a lavender tinge to it, but the corona is fairly white.

The flashlight is designed so that it can be stood on its end and used like a candle, with the beam aimed at the ceiling. Doing this at night, I found it dimly illuminated a 20 x 30 foot room. The lighting was sufficient to easily see all the furniture and avoid bumping into anything, but most people wouldn't be able to read, of course. Used as a candle in such a large room (600 square feet), it's more like a night light on steroids. Used as a candle in a normal-sized room, like my bedroom, the room is more brightly illuminated (not simply like a night light on steroids). Used as a flashlight in a bedroom or closet, it works quite well.

I compared the beam to that of a lower-end flashlight that I bought at a local retailer. The lower-end flashlight has 9 LEDs and three AAA batteries so it is not surprising that it offers better light (a brighter and wider hotspot) than the Fenix E01 (which uses one AAA battery and has one LED). The lower-end flashlight is cheaply made. For example, the on/off button for the lower-end flashlight doesn't always work the first time. And it's bulkier. The lower-end flashlight's claim to fame in this case is that it cost $2.99 (and came with three AAA batteries).

Given that cost difference, why is the Fenix E01 a fair value? Because its compact size and light weight make it much more convenient to carry it on you at all times. (Carrying something on your person every day is sometimes referred to as Every Day Carry, or EDC.) In addition, its more reliable construction adds value.

One reviewer suggested keeping one of these lights in emergency kits. I can't agree with that. If I were preparing an emergency kit, I would want at least a 2-cell flashlight with variable light output that has AA batteries, which offer the potential for more light output or greater battery life (and maybe both). Of course, those flashlights with variable light output are more expensive, but I am confident that a simple, fixed-output, well-made 2-cell LED flashlight that uses AA (not AAA) batteries can be found at close to the price of the Fenix E01.

If you are not going to EDC this flashlight (say, for example, you intend to keep the flashlight in a desk drawer or in a glove compartment), then you might be better off with a 2-cell flashlight where you get better performance and don't pay a premium for small size. Furthermore, while the Fenix E01 is light, a slightly longer flashlight would probably be easier to carry in hand for an extended period of time.

One plus of the light not being too bright is that it makes it easier to read in the dark printed materials that are illuminated by the light. A dimmer light is also more useful when you're crawling under a desk trying to read the labels for jacks on the back of a computer. Sometimes the brighter light will cause glare that makes reading difficult. And if the flashlight is used to navigate a darkened bedroom at night without disturbing your sleeping partner, being less brilliant is better.

All in all, this is an excellent flashlight if you want to carry a small, lightweight light with you at all times. For nightstand use, it can't be beat.

UPDATE:

I also have taken this light with me when traveling, and it is perfect for a carry-on bag when flying. It takes up almost no room and the weight is insigificant. When traveling, I keep it in my pocket, and it is fine for illuminating a path. I was in San Miguel de Allende, Mexico, the streets and sidewalks are paved with stones, which can be quite irregular (not to mention the occasional hole), and the street lighting is not consistent. I put the Fenix into my pocket when going out at night and didn't even notice that the flashlight was there. But when I needed it, it was perfect for the task. My sister was using a MagLite Solitaire, which was pathetically dim in comparison.

At this price, my only complaint is that the round body allows the flashlight to roll too easily. I have to be careful when placing it on a nightstand that it doesn't roll off, particularly when I reach for it in the dark and hit it with a finger but can't grasp it. To keep it from rolling, I put it next to something that will keep it in place.

As evidence of my opinion of this product, I'm buying another one to give to my sister.

FURTHER UPDATE:

I have finally figured out a cheap and simple way to keep the flashlight from rolling. I took a split ring and attached it to the base of the flashlight. A split ring is often used to attach keys to each other or something else. In my case, I took a split ring that was used to attach my car key to a parking stub and used that. (You can't get cheaper than free!) It's about the size of a nickel, and being of thin wire, it weighs almost nothing. There is a small hole at the base of the flashlight that that allows you to fit one end of the ring through, and then you just turn the ring until it's all the way on. The hole in the base is really small though, and a more substantial split ring might not fit.

If I flip the split ring on under the flashlight when I lay it down, it won't roll. If the split ring is not flipped underneath, then the flashlight will roll a little, but the ring usually stops it after a few revolutions. Having the ring on the base of the flashlight makes it easier to fish the light out of a sleeve in my carry-on bag that I slip the light into. The ring does not interfere with standing the light on its base so it can be used in candle mode.

I have updated my rating to five stars.

There are brighter lights, there are larger lights, and there are much costlier lights. I know, because I own all of the above and many more. But, this little gem cannot be beat for a very lightweight, bright-enough keyring light that you can always have with you, that you can turn on and leave on for over ten hours with constant brightness, and then still have another five hours of fading but still usable light to read a map with or signal with. All this for the cost of a single AAA battery.

This is the light to keep in your pocket all the time. And, at this price, you can afford to keep one for each family member in case of power outage or other emergency. It's as simple as that.

Fenix offers two keychain LED's. The E01 is a good light that I'm happy with, I also bought the Fenix LOD for another set of keys. If budget price is what your after in an LED, get the E01, you won't be disappointed. If your looking for the brightest and different light settings get the LOD, more money but a far superior light.