I got one of those a few weeks ago, and liked it so well I immediately went and got a second, for my wife's minimag. I padi $10 for each, here in Juneau, Alaska, where every thing is higher except your paycheck.
First, about the light:
The beam is broad, even, reasonably bright, and not too blue. There's not much throw. It'll let you see the trail 10 or 15 feet in front of you, or dimly light up the far end of the cabin, but you're not going to be lighting up the black numbers on the black house across the street (one of the things I used to use a flashlight for). It seems to be completely unregulated, but what do you expect for $10?
We went on a church retreat, staying in cabins with no electricity or plumbing, and used that to see our way to bed at night, and to the toilet building. It worked well for walking down paths in the dark, for lighting up the cabin enough to see the bunks and get undressed and for reading to the kids.
The LED module is nothing really great, but it puts out about as much light as the minimag (maybe more, but minus the throw), and for $10, it's worthwhile.
Now, the clickie:
It's aluminum, with a plastic button. Looks much more solid than the pictures I've seen of the kroll switches. The edges are knurled. It's neatly done, but a much rougher knurling than the rest of the light. It's good, but looks slightly out of place. Not a strong criticism at all.
The switch protrudes enough that it _might_ turn on if you stick it in a pocket with some other junk. I've carried it in my hip pocket, tailcap down, without it switching on. The switch seems to push very easily, but makes a slight but definite click on or off. I don't get the feeling that it's fragile. You can't stand it on its tailcap because of the switch, but you really couldn't do that with the original tailcap, either. The new reflector is just right to let you stick the butt of the flashlight into the head, just like the stock candle mode.
It has an o-ring where it belongs to seal the cap-to-body threads, and it may be adequate to seal out water if it gets dunked. The plastic switch button doesn't feel as if it has an o-ring, so the switch mechanism would probably get wet if you dunked it (note to self: don't fall in the water). The hole where the spare bulb is kept in the original tailcap is filled with what looks like black epoxy or so, with the spring rising from it. If the tailcap-to-body o-ring does its job, there won't be any water getting into the body when it's dunked.
This switch would be pretty high priced at $10, compared to the $5 or so I've seen the kroll going for, but I suspect it may be more solid than the kroll. I've heard they have a short lifespan, and I could imagine that this one won't (and I could be wrong). With the LED module, it's a great deal.
Summary:
This isn't a high end kit, but it's so cheap that I don't care. It really improves the minimag. If the switch turns out to be short-lived junk, I won't feel badly cheated.
You'll find a review with pretty pictures here:
http://www.britishblades.com/forums/showthread.php?t=10528 . He liked it. He's wrong about no candle mode.