The speaker is round, approximately 3 inches in diameter, and has a suction cup attached to the back so that you can stick it on the wall. It comes with a charging cable that has a standard USB connector at one end and a mail plug similar to that on a wired headset on the other rend. I would prefer a standard connector for charging, since having a proprietary one means you have to keep it with you if you will need to charge the unit and if you lose it you're toast. However using the smaller plug probably helps keep the unit as water tight as possible. The manufacturer says the speaker will float.
The controls on the unit are discernible by feel, but it would be nice if they were just a little more pronounced. You may have trouble feeling them if neuropathy keeps you from reading braille. They are on the front of the unit where you would expect to find a grill. If you orient the speaker so that the plug cover is on top, the configuration is like that of a directional keypad. The play/stop button is in the middle, the back and forward buttons are on either side. The power button is on top and the phone button is at the bottom. Yes, you could answer the phone from the shower. Good thing there's no camera. You can also address Siri, though I have not tried this for accuracy.
There are no voice prompts, but paring is simple and sounds let you know when it has been accomplished. There is no audible indication of the battery state that I am aware of, though I have not drained the unit to the point where it might give some indication of low battery.
The sound is surprisingly good for the speaker's size. The suction cup works well even if the surface is damp from condensation. Make sure you have a good grip on it when taking it down, but mine survived a 5' drop onto tile without any problem.
Finally, the reason I decided to write this review, the company sends you, unprompted, a PDF copy of the manual. This was through Amazon, but I assume they do it any time they have access to electronic communication with you. I will say sending it in 3 different email messages is overkill, but it's not exactly a huge file. The PDF is not tagged but is otherwise easily managed with a screen reader. Amazon lists the retail price of the unit at $109 but is currently selling it for $29.
I would definitely buy this again, but I don't think I'll have to, at least until the battery gives out.