This pocket sized marvel is outstanding! Considering it's only one speaker and no bigger than a pot of vitamins or a jar of ink, it packs quite a punch!
We put it on the arm of the sofa initially to test it out, and you could feel the bass vibrate through the whole thing. It seems to not only be pretty powerful on its own, but borrows the surface it's placed on to amplify sound even more.
If you're looking for a sturdy, well built, pocket sized speaker for your iPhone, Kindle, laptop, or indeed anything with a mini jack, then you're probably not going to find much better than this little guy. Love it! I used to take an iPod and dock into college to play music to the class, but this thing is far superior and whole lot more portable.
My only gripe, and this is more to the manufacturer than about the device, is that considering hardly anyone actually reads the instructions on these things (well most blokes anyway), having a diagram showing the device being stretched under the words "Before Use" is a really bad idea! When it is actually open, you can only see about one crease of the diaphragm unit, but the diagrams show it with four and the warning diagram makes it look like a mini accordion. So Mareware, fix your diagrams and put a big warning X through the warning one! Seriously it currently looks like and instruction to do the very thing it's warning against!
That said, awesome speaker!