This light was super bright while it lasted which made it great for biking on unlit streets. Also, for the half year that I had it, I never replaced the batteries which probably would've needed replacing at least 3x if it hadn't been an LED.
HOWEVER, it broke after dropping about 3 feet onto the ground, which is simply unacceptable. REI, being completely awesome took it back with no problems, but its dissapointing somethign at this price point could break so easily. I'm guessing and hoping I just got a faulty one though. It felt well made, and there was no obvious physical damage from the fall, so it was something electrical and internal (which is why I couldn't fix it and had to return it).
I'd highly recommend it (or the EL510 which is its replacement) for anyone who bikes in places without street lights, however if you only bike occasionally, or bike under some kind of lights, you can probably save yourself some money and bulk and just get one of its cheaper cousins such as the EL 130.