I recently ordered a pair of these to light up my wife's bike who bikes home with my daughter each evening. Now that it's getting dark earlier, I want to make sure side visibility is sufficient, since I already have headlight/tail lights. These were fast to install, quite bright, and the hub mounted battery keeps it from making the wheel wobble at high speeds. I am impressed with these!

I've been riding a bike to work every day without fail for at least the past 5 years, and on and off before that. I am convinced that some kind of spoke light is a necessity for any after-dark riding. I've previously tried the Spokelit-style lights, a knockoff LED spoke light, and LED valve caps. The MonkeyLectric 40 is the best spoke light I've been able to find so far, although there are a few improvements that could be made.

What I like:
1) Build quality (mostly, see below). The parts all seem rugged, with no weak points that could break.
2) Brightness. I was worried that only 4 LEDs would not be enough, and spent quite a bit of time deciding between this one and the 8 LED version. In the end, I wanted a smaller light on my spokes so went with the M204. I didn't need to worry; this light is so bright it lights up the ground around my front tire as I ride. Super visible. Provides more light than any other spoke light I've used. It's bright enough that you really only need one.
3) Battery life. I changed the batteries *once* this season (I only use them during my evening ride, and only from October-ish to March-ish). With the cheap LED knockoff I had to swap batteries once every few days. The valve caps lasted maybe 3 weeks. The Spokelit-type lights performed better, but take watch batteries and throw much less light.
4) On-off switch. Both the valve caps and the LED knockoff came on "automatically". The valve caps came on whenever moving. The LED knockoff supposedly only came on in low light and when moving, but was unreliable (usually ran whenever moving). This caused frequent battery changes.
5) Simple control of lighting color and pattern. The LED knockoff didn't have a selector switch. The colors for the M204 are quite nice looking, and I like the ability to pick an LED color that matches the rest of my bike.
6) No issues with rain/water. Rode this light through some serious El Nino rainstorms this year with zero problems.

Here's what I wish could be improved in future models:
1) Terrible fastening system. First off, mounting is kind of a pain. The spoke mount isn't bad, but I succeeded in jamming my hand into my spokes hard enough to draw blood when trying to get a tight fit on the hub-mounted battery pack (pulled on it with needle-nose pliers, which slipped, of course). I get that zip ties probably a) make the product cheaper to produce and b) provide much stronger fastening than other spoke-mounted systems (usually either simple "tension" from the spokes or a plastic screw), but it makes it near impossible to easily remove the light. In concession to this fact, MonkeyLectric provides a metal band that you can use to add security, but I actually don't *want* more security, I want to be able to move the light quickly, either to swap to another bike that I might ride that day or to remove because I don't plan on using it. All my other lights have quick-release systems that make this possible -- I would actually be happy enough with some kind of screw/allen wrench mounting system for the light and the battery pack (much like the ones you see on rear light mounts), no need for a quick release, although I expect it would be possible (e.g., the Planet Bike quick cam release system they use on their lights). Heck, I would even be OK with the stretchy band type system you see shipping with super cheap bike lights. That said, the removal wouldn't be such a big deal except:
2) This lighting system is really unfortunate looking. Even though my bike is a commuter, I've spent a little bit of time making it look nice. I wasn't happy about zip-tying a big honking battery pack to my hub. The problem here is really with the battery pack -- I actually don't mind the looks of the light itself, it would have been nice if there was a way to incorporate the battery into the light somehow. Looks like they did this with previous versions but stopped -- I'm guessing it was to standardize the battery pack, giving it the ability to store more battery power and make it work with more of their product line. I would've traded the battery life for a nicer looking solution (ideally, integrated into the light, but would even be ok with a short wire to a spoke mounted battery pack). I'd also prefer to have it take just one battery instead of three for weight and appearance. As is, I'll probably be removing this at the end of every season. I'll then have to remount it each year, and also not get to use it those rare times I'm out after dark past the daylight savings switchover. My other lighting mounts stay on my bike year-round (often, though not always, with the lights still in them). Additionally, I'd *love* to run two of these (back and front), but due to the mounting system and looks I don't really want two of these on my bike.
3) Other battery system annoyances. The battery pack has two plugs so you can expand your system later. Cool! Unless you choose to stick with one light. Then you have an empty plug that just flopping around of the back of your battery pack. I attempted to tape this down with electrical tape, but it's difficult to make that stick (particularly during the rainy season). Would've preferred removable plugs, so I could take the one I'm not using out although I expect this would add to the cost of the unit (you'd probably also need a cover to prevent gunk from getting in). The other problem with the battery pack is that it often slips around the hub (since the mounting system makes it difficult to get it tight). This increases the slack in the wire, sometimes to the point where it periodically slaps against some of the spokes, making an unpleasant 'tink tink tink' sound while you're riding.

Overall, I really like this light. I actually bought another as a gift, and will advise others to purchase this brand. Hoping in the future they'll be able to add in some of the features I mentioned.

These work great and were a big hit on Christmas with the kids. They are very well built and pretty easy to install, It took me less than five minutes. It is true that you don't get full look of the continuous lines on your wheel unless you are going very fast, but we bought them for safety and they serve that purpose very well and the kids love them. This was a great purchase!

The lights were easy to install and very bright, making me much more visible on my bicycle on my ride to work.
They'd have gotten 5 stars, but the pictures are misleading (as others have pointed out). For most cycling, you get what appears to be a blinking bar at different points around the wheel -- still fine for being seen but not what's on the pictures.

If you're fine with that, then this is a great product that I'd recommend putting on your bicycle.

very cool product and idea. It's better to be seen from the side in many cases, and this product does a great job of drawing attention to the bike and rider in exactly that situation.