I bought this to replace my speakers when I noticed that the power supply wire was damaged. I decided to go for USB powered speakers as I don't use the computer for serious listening and would rather reduce the number of transformers connected to my plug sockets! Also my other computer came with similar speakers and I am quite happy with those. They could also come in handy for those people who use a laptop.
The speakers are entirely USB driven, using digital audio output as well as power from the USB port and they give a surprisingly good and crisp sound, though you can't expect to get deep bass sounds. No installation was required apart from plugging in.
The main criticism of the unit is that it does not have a volume control knob or an on/off facility, but instead relies on three knobs to raise, lower or mute the sound, operating directly on the windows sound control in discrete jumps. As a result you cannot fine-tune the volume without accessing the relevant control on the computer, and you can't turn it off when you don't need any sound. Also I am not keen on the light advertising its digital sound, which is always showing.
When the unit arrived there was a a fault in the speaker on one side, evidenced by a slight rattle when playing deeper sounds at any volume, so I had to have it exchanged. I am sure Logitech should have done a better job with their quality control. Fortunately Base were very good and gave me a replacement without any quibbles.
So overall I would give this 3 stars. Hopefully Logitech will address the issues mentioned, but who knows?