Turn the volume all the way up and march around your house playing "Scotland the Brave". It'll make your day.
Doesn't annoy the family as much as synthesizers that make noisy hard-to-tune sounds.
Takes about 10 seconds to boot, unfortunately. Once it's running, choosing a sound and playing is easy. Recording loops seems easy enough too. Fooling with the effects looks hard without the manual in hand (though there may be no real reason to do that.)
The clip makes it easy for two people to play at once.
Maybe playing with a stylus just isn't very satisfying.
But someone else might have better luck with them.
The one little keyboard covers several octaves, so don't expect to be able to get specific reliable pitches out of it.
As with the other monotrons the headphone output is pretty noisy.
You can get a lot of sounds from the small number of knobs, from very noisy to something that could carry a tune.
It's possible to play a mostly-accurate tune on the keyboard with some practice, or have fun sliding or wiggling your finger around.
It's more fun if you have on hand some miniplug patch cables (and maybe miniplug-to-1/4" adapters?), so you can plug other stuff into it. (Might be nice if the library could include something like that.)
The headphone jack has a pretty annoying hiss.