Tinker Juarez uses it. What more can I say. Prior to rock'n'roll I would take my chain off and clean with degreaser very frequently (weekly?). With this stuff I lube and wipe down like the directions say...probably every 100 miles. Its very dry and dusty here, so I can't comment on how it does in really wet conditions.
I've run a few different popular chain lubes on my mountain bike. R&R Extreme is by far my favorite chain lube. It keeps the drive train quiet and smooth. It doesn't attract too much junk when the trails are dusty. I've run cleaner lubes but they don't last half as long. For best results you really have to pour it on like the directions state, so a bottle goes fast.