OK, there are not that many features, but the sound quality is excellent. I have compared this 4kg speaker to the much heavier Behringer PK108, Fun Generation PL108P, Fun Generation BP108A and The Box Pro Achat 104, and this has by far the best audio quality, with the Behringer PK108 coming second.
The maximum Audio level is about 100 dBA at 1 meter distance, measured with a proper sound pressure level meter, in the middle of my living room. The audio level drops to about 80 dB at a 5 meter distance.
The frequency response is excellent, and the bass is remarkably punchy for such a small loudspeaker.
I would give the audio quality 4.5, because the bass is slightly muddy at higher output levels, but the "peak" in the bass can be equalized away.
I will keep this speaker, and sell off the other 4.