I have used this device with a 12-string guitar in a duo with an electric harpist. We make ethereal music that evokes space and cosmic vibes (man).
Detailed demos will show you the basics of what it can do. You will have to find out for yourself just how subtle the settings can be, as the results will be different for every instrument and musician. Basically, though, it's about loveliness and dwelling on dreamy sounds.
What we have here is a collection of good reverbs, some quirky variations on the reverb theme, and a widely adjustable shimmer that pretty much justifies the price on its own.
I have compared the quality of the basic reverbs and the shimmer with lo-fi units; it's in a different class altogether. Compared with the kit that we drool over: OK, there's amazing stuff out there, but in a real gig situation the Joyo will blow people's minds and they won't be wondering whether a £300 unit would have done it better.
From now on I'm going to be using mine on the "wet" output of a MEL9 and applying other devices on the guitar signal. That's until there's another change of mind...
For presets we would have to pay more. So write down your settings and take 10 seconds to set them! It's not hard.
Seriously, if you wish to explore the potential of reverb in your music, consider this amazing, delightfully affordable box of wonders.