It's a beautiful instrument with, in my opinion, its greatest potential in jazz and
jazz-like music where you can easily discover the greatness of its sound. Personally, I love improvising along with Django Reinhardt's music. Only your fantasy (and skills) will set the limits for you. Unfortunately, it has some weaknesses. The Low C# tone is really weak, at least on mine. I haven't compared to anyone else's. Furthermore, it's hard to properly hit the notes on the higher octave. If you prefer a little deeper sound, I'll recommend you to go for the Bb. However, it is a small instrument which should fit really small hands, even without exerting oneself. Practice alot and this instrument will perform magic!
A booklet will come along with the fingering charts and further information about the instrument, but unfortunately, it's just written in German. I advice you to consider its accuracy to hit the perfect pitch as this is what I found the most troublesome part of the instrument. Being a brass player might help you on your way. I am, since long, a woodwind player which I think made me experience the Xaphoon as a bit inconvinient. But I'm getting used to it! Also, make sure you keep the mouthpiece as clean as possible.
Good Luck!