Tracking - stable and smooth across the whole fretboard (for both guitar and bass). Chords can get messy but that’s down to the sound used rather than the tracking I think because some are also very clear and precise.
No discernible background noise.
Huge range of sounds from 11 groups, each with 11 variations ie. 121 separate sound sources before you move any of the controls. They are pretty impressive too and, generally, very usable. The controls change a variety of things, depending on what sound source you are using - rate, tone colour, depth and pitch on some. Natural guitar and synth sounds are easily blended.
Take a look at the sounds on offer from the Boss website and you see what’s there. I particularly enjoy the sequences - very inspiring.
The only downside is the inability to save presets. I can see myself taking lots of phots of settings
I nailed the intro to the Who’s ‘Won’t Get Fooled Again’ in the shop but can I remember now - no ! I’ll remember to grab a pic next time 
All in all it’s a step beyond anything Boss have done in the compact pedal synths before. Great fun, encourages creativity and I am enjoying every second with it.
