Before getting into this product: I would just like to say I tried a budget speaker, and I am not going to even tell you which one. It was really bad! Not to say that this speaker is expensive, but going much cheaper was not a good idea!
Luckily after my first failed attempt I found that Anker was getting great consumer reviews across all their products and decided to try their Bluetooth speaker.
It paired with my devices in seconds, and switching the pairing to another device was just as simple with the Bluetooth button on the machine. I was very surprised as not all devices pair this easily!
I haven't actually timed how long it will play for, but it is a LONG time, and it can play sound while it is charging. This alone should alleviate the worry it won't have juice when you need it.
When paired with Bluetooth the volume control is done from the phone / tablet / computer. I love to have the remote volume control as the Bluetooth range is rather large for this speaker.
Lastly, the audio quality: It is rather remarkable and LOUD for such a little box. If you want a nice speaker for the car, pool, or even travel as it is very compact, I would buy this product again in a heartbeat!
Update: After using the product for a time, I use it everywhere! Sometimes when I am working around the house I grab it and carry it around so I can listen to audio books. Also, while camping given it's crazy good battery life and USB charging, it is a great companion to bring your tunes to the lake/river/ocean =)