Got one a month back, have since had opportunities to try it out in lots of different situations, so let me tell you what I think!
Here's what it looks like in the box:
The base and plug is exactly like any conventional H4 bulb. If you can put an H4 in your headlight, you can use this. If your headlight has that rubber cover over the back of the housing, you'll probably have to trim it so the fan can stick out (I did).
(picture makes it look yellow, it's not. Pure white irl)
Lo
Hi (sorry, people in that house)
So far it's been fantastic. I had a sylvania H4 in there before, and I basically rode with hi beams on all the time because it was piss weak. It barely even looked like "light" during the daytime at all, like here in this pic it's barely brighter than the sunlit areas.
It's fantastic during the daytime. It helps you stand out so much more during times like sunrise/sunset, because the light isn't yellow. LEDs are also super directional, so you're not really blinding anyone unless they're crouching down 100 feet in front of the bike. Like, I've been blinded more by crappy HIDs and those super bright blue projectors some new cars have (I'm looking at you, hyundai!!!)
The only downside is that you won't get 100% function unless your headlights also come with an LED reflector inside - without it, the light will have dimmer spots within the circle it casts, because LEDs need an entirely different reflector (since they're so directional). You can see a bit of it on the ground in my night pics up there, but that's also partially because my garbage delkevic headlight reflector is bubbling in like 4 places. Basically, with a conventional reflector, your throw/spot light will still be good, but your spill light won't be as good as it could be. Cyclops includes two different thickness spacers with the kit, which are supposed to help alleviate it somewhat. I haven't bothered putting the spacers in, because the light is real freakin good anyway.
It will cast light on my shirt during the day if I walk like 3 car lengths in front of the bike. It made what would have been a miserable, slow, eye-straining 90 mile trip through a HUGE downpour on unlit pitch black highway at night, into a joke. I emailed the company with a question at like 7 PM their time and got an answer in 5 mins. The fan makes an adorable "wheeee" sound. It's pricy, but worth it.