Got it last night. Irritated that there's no AUX to be able to learn songs for practice, and my experiment with a 3.5-USB-C cable did not work as an audio input. I don't have an amp at home, so the aux/phones are pretty much mandatory for me. $60 for an added BT receiver, I suppose, but still...
The sounds generally seem like an upgrade from my trusty old ME-50B. There were some occasions when an effect did not seem to turn on/off with a footswitch (like hitting some distortion on the fly), like with the instant 50B, but that might be my not reading the manual. In one case I couldn't get the octaver to stop - I may have been in the Memory Mode, but it's hard to tell. An effect would sometimes need a knob twist to kick on, it seemed?
I do like the one-switch tuner and the distortions are definitely improved, to my ears. There are some oddball effect additions which I cannot imagine anyone would use, like Slicer or Ring Mod. All the usual BOSS goodies like Chorus and Delays are quality.
So far, it's not a home-run replacement for my very giggable, durable 50B, but we shall see.