I've had this light for about 3 months now, and I like it.
The beam is very bright indeed, so much so that you may need to be careful to avoid dazzling other road users. If you use it in flash mode, you might get a retina image if you let it catch hold of any reflective road signs. It's so bright that I think it even helps with making you visible from behind because of the beam it throws forward.
The battery lifetime is great (I get around 60 to 70 minutes on full power before the switch starts flashing red to say you should recharge), and the ability to recharge via USB is soooooo convenient.
I have used it in some atrocious weather, and it has not missed a beat.
Now the niggles -
NIGGLE 1: the little rubber plug thing that keeps the weather out of the USB port fell off and got lost after about a week. I don't think there was anything wrong with my particular light, I think it's just a little too flimsy. Annoying when you consider the price. To stop the weather getting in, I have made a weatherproof sleeve out of the finger of a black heavy-duty washing-up glove, works nicely and probably better than the original plug thing anyway.
NIGGLE 2: the screw thread on the handlebar mount has already succumbed to the road salt. Again, annoying when you consider the price. My advice: give all your threads a liberal coating of copper grease when you first attach the mount, assuming you want to get it undone again at some point in the future.
But the light itself is so awesome and the niggles so easily surmounted that I still like it overall, even considering the price.