A great unit, well worth the price.
Battery is quite long lived, sound volume reaches fairly high level, if not exactly “high fidelity,” and the suction is amazingly secure (the cup is nearly the size of the entire, very-light speaker).
My sole hem and haw; the forward and reverse buttons are the same as volume up and down. Therefore, it’s very hard to use the volume incrementally - because pressing the buttons once engages “next selection,” or “last selection,” instead of one volume notch up or down. So you need to hold it down, guessing where you want to stop the volume.
First world problems. Not a big deal at all, really.
Otherwise, I was amazingly surprised at the quality for the price. A waterproof, rechargeable, bluetooth speaker, with controls, for 10 bones? A no-brainer, if you listen in the shower.
IPX4… Waterproof… pick one.
That’s a lot like my Ecoxgear waterproof Bluetooth speaker - you can’t just nudge the volume up or you wind up skipping the track you want to hear louder. PITA. My wife once got me a really nice wireless shower speaker that had individual controls and did everything well, except resist falling down a flight of stairs and landing on concrete. We haven’t been able to find the same model anywhere to replace it with 
mine had godawful sound quality. It’s water proof and fine for podcasts but worthless if you want to listen to music.