This pedal blew my mind! I had upgraded from a TS-9, and the Amp11 absolutely delivered what I wanted: "tube amp nearly breaking up", "low gain overdrive that responds to my playing and responds to the guitar's volume". All those things that I wanted from my TS-9 but never got it, the Amp11 delivered immediately. Not a TS-9 clone though, as this is not a midrange-booster.
I read somewhere that the strength of the Amp11 is that it does not sound like a pedal, but rather a tube amp. I didn't really understand that statement until I plugged it in: with a transistor amp (Roland Jazz Chorus) the Amp11 took me the closest to a real tube amp sound as one can get.
The Internet community blames this pedal to be a Timmy clone combined with a booster, but I don't care because the Timmy is extremely hard to find an also extremely expensive, so the supposed similarity might be a good thing from the user's perspective.