This new "amp in a box" line is overall great. I had the opportunity to try the jcm800 as well but eventually opted for the jvm instead.
The pedal is very sturdy, metal casing. The presentation is nice as well.
The sound is big, thick and heavy on the bottom end in classic jvm style, but the tone knob can clean up pretty nice. The gate is a very welcomed feature, and it works great.
It can easily do crunch tones as well, but I think it gives its best, with the gain cracked past 7.
Overall I'm very pleased, it's a great pedal for a good price.