There's a feature on this device that is somehow not mentioned at all in the product description, or even the small manual that came with the device. As shown in the above picture, there's a MicroSD card slot, something I've never seen before on a Bluetooth speaker, so I tested it out. I just loaded a few MP3 files, inserted the card into the slot, and it was able to play my offline music files without any Bluetooth connection (see the included video for how it works). I'm not going to run the battery down trying to see how long it can play Wallspin by Neil Cicierega in "SD Card Mode", but I'm assuming that it's far longer than my observed or the advertised battery life.
Speaking of battery life, I've been able to run a white noise generator on the speaker at a reasonably high volume for over 12 hours so far, and the speaker is somehow still reading 100% battery. I'll update this review once I've completely drained the battery and then recharged it with my charging meter to see the full battery capacity of this speaker. So far, it looks promising.
The build quality seems good. It's a dual speaker design, with a 'subwoofer' where the lights are, and a primary speaker on the other side. The plastic rim seems to pick up fingerprints easily, kind of like the plastic on my Dell XPS. The buttons on the top don't feel mushy or unresponsive, and the side panel covering the ports is a thick thing of rubber that stays in place. I would have liked a USB-C Charger in 2020, but a Micro-USB is just fine for a reasonably priced compact speaker.
There's three ways to play music on the device: Bluetooth, AUX 3.5mm jack cable, or USB. That's a wide range of flexibility, some of which don't require this to be used with a phone. Gives me a lot of options, which is great.
The lights that respond to the music can be hit or miss. If you're listening to something with clear beats or base hits, it'll be fine, but something like classical music will make no sense. That's not a shortfall of the speaker, there's just nothing for the speaker to pick up on. This is just a minor thing, and truthfully, I don't see myself really ever using it. I got it for the music, not the light show.
Overall, I'd highly recommend this speaker thus far. I'll update this review if anything changes, but it looks like a solid choice thus far.