This little speaker sure has sound! It can reach quite high volumes on its own and it's very easy to connect several speakers together if you need a bit more sound. The sound is very clear and even has a little bit of bass thanks to the bit of space it gets when you open it up.
It's very solid and the battery's charged via USB. One charge lasts about 8 hours of continuous play, but I've found it to last a good week and a half of playing whilst I'm cooking dinner everyday.
One thing to note is that due to it being a single speaker it plays everything in Mono, I didn't find this to be a big deal but some might. This is still the case even when you use a second speaker (or third or fourth etc.) with each one playing a mono rendition of the song. X-Mi has a different model which you buy as a set that is capable of stereo sound, but it isn't as convenient or as compact as the X-Mini II.