I have two, each are a different style on a couple different bikes.
On my '03 I have the Endurance model (battery operated only) and the '99 has the Vapor model.
Vapor runs off bike power when the bike is running as the 99's from the factory do not have a battery installed on the bike. The '99's WR's are AC ONLY. I like the Vapor MUCH better. It has more features, is easier to operate, as well as set, and goes a lot longer between battery changes as it's battery is just back up rather than full time. The Vapors also run on AC or DC so will fit either bike!
I like it so much I have bought a Vapor to update the '03 to, but have not gotten to that installation yet.
I agree with the previous post from flyandride in that the plastic mounts included with them are pretty cheap. I also built my own mount but used a couple inches of inch by inch by one eighth inch thick aluminum angle. I mount them both right behind the front headlight/number plate plastic to the top triple tree using an existing hole that was there so they are pretty well protected.
I have crashed and beat the crap out of them for several years and have had no issues whatsoever. They are spot on
both in speed indicated as well as odometer reading once you get the correct diameter of your wheel
plugged in to them too.
For the money and ease of installation I do not think they can be beat.