I have a first-gen set of Revolights, which I still REALLY like. As stated by others, they are designed more to 'be seen', but seem to catch people's attention quite well. I've had many folks stop to ask me about them. In addition to my Revolights, I run a NiteRider 700 headlight and Niterider Solas 40 taillight.

While the first-gen work fine once they are installed, the newer Skyline/Eclipse versions are much easier to install. And with the Eclipse now having the battery on the ring, you can remove the battery much quicker and lose the wires and hardware for mounting the battery on the hub.