They're a great little unit for $60 used.
They're the cheapest way to get a loud amp to be tamed down, in addition to adding reverb. Since it has a mix control, you can keep the reverb subtle. Then with the input and output knobs, you can get the signal nice and hot with the input, and lower the output, so it acts as a secondary mastervolume on your amp. You can make a halfstack more useable in a bedroom, using the nanoverb for that purpose.