I was surprised that it's brighter than the MagicShine. I was also recently told that it was "the same LED as in the Cygolite Hotshot" - if so, they're either driving it harder than Cygolite does, or their optics are better. Their optics are certainly better than the Hotshot at dispersing to the side, but clearly it's also significantly brighter even on-axis.
I think in the budget category the Hotshot is good. I like the Knog Blinder but the mounting is pretty flimsy and non-flexible - you need a seatpost, period. I've heard LOTS of people say their Knog mounts broke in less than a year. Knog really needs to step up and make some lights that mount some other way than with a rubber band.
EDIT 4/10/2013 - first morning out, in the rain, I had the Serfas on the belt clip on my wedge pack, and it flew off when I hit a hole. I don't think the belt clip is to be trusted at least on thin, smooth straps.