I would not feel comfortable with having one of these as my only be-seen light. It's a tiny light for use as a backup, for side visibility, or extra conspicuity. On the other hand, they do mount nicely around all sorts of irregular places. Like fork crowns or seat posts.
My biggest critique is the same thing as my problem with most lights. I'd really love it if there was a light that would wrap around a mountain bike suspension fork blade.
My second critique is that, for a single super-bright LED, battery mount, and waterproof case, this costs a LOT of money.