It doesn't include a speaker. The included amp is certainly enough to hear what you're doing, but won't really give you any significant bass--using something else will make it sound much better.
Maybe I should give it another shot. Druillet seems to be an important creator, I'm glad we have some of his work.
I'm enjoying it, but be warned that it's still in progress. (The library has 3 of 4 volumes published so far, and I believe more are still to come.)
It sounds great. I like that you could probably fit it in a (large) pocket.
There are a lot of options. Buttons and keys often have multiple uses, and I don't find the interface terribly intuitive, so you'll probably want to read the manual carefully if you want to learn all of its features.