Hmm this is an interesting one...I saw these in duty free a while ago, and I thought these could be good, but not able to actually her one in action (and at 29.99 quid) I thought it probably isn't worth it.
It was on sale here for about 11 quid, so went for it. This thing is great, totally neat product. I get a little bass rattle / distortion at high volume (might be just my one), but it doesn't matter coz it's loud enough.
I just wish I had one of these the days we sat in the park messing around drinking etc. I'm pulling it out this summer, might buy another and daisy chain them...what a cool feature!