I bought this product in a previous woot sale. I was surprised by the build quality of the speaker and it gets much louder than I expected, especially considering its small size. Sound quality is good but don’t expect to hear much below 80Hz or so, but that is a simple consequence of physics.
The controls are more thoughtfully laid out than those found on many other speakers in this price range. For instance, volume and track control have their own buttons - I hate devices that force you to use the same button for several functions.
There is a power meter that doubles as a volume indicator, which is useful. There is also a handy folding carabiner on the back.
The speaker is rugged and can probably take a lot of abuse, but its biggest selling point is that it is seriously waterproof. You can throw it in a pool or drop it in a lake and the speaker will be fine - it floats too.
I like the voice prompts, but they are loud. Battery life looks to be 4-6 hours at medium volume levels.
The speaker is a good deal for $40, especially if water resistance is important to you.