Overall, really good for bringing up the quiet parts while keeping the louder ones under control!
One of the pieces of gear I took the longest to get to know and use. Maybe it's just the nature of a compressor, but I could never really get it to do exactly what I expected it to do. This, however, was most likely because of my unreal expectations (I expected something probably more along the lines of 'never ending sustain').
What I found it was great for, however, is more along the lines of what a compressor actually does (DUH), and that is bringing up the quiet stuff while keeping the loud stuff at a similar level.
To me, this is incredibly obvious only when tapping, otherwise I have to really try to emphasize the dynamicness while picking. This is probably just my untrained ears though.
I also found it useful while playing with bandmates as it made sure I was around the same volume all the time.
Another thing you could use this for is to have it set up after your drive so it squashes things down a bit, but not too much, and reduces volume a bit, and use that as a rhythm tone, and then turn it off for the lead tone, which I did for a while as well. Works great if you don't do a lot of legato, in my opinion.
Only thing I wish it had was a blend knob because it would make it much easier to see what it's doing, in my opinion.