I needed a mouse for my laptop and couldn't be bothered to go out of the house to buy one. Seeing this on here for under a fiver, I thought it was at least worth a try (and I expected it to be quite shoddy).
I was very pleasantly surprised when it came - worked within seconds of being plugged in and never had a single problem. Great size - not too small, and very ergonomical. I thought the lights were a really cool feature; it didn't look like the sort of thing that had been assembled togteher at a cheap price with a few dodgy LEDs as I initially feared. It only added to the sleek look of the device which you could easily see on a designer shop shelf for £20-30. Being optical, the movement was constantly smooth and running solely off USB power, there were never any battery flaps or other problems to get in the way. Having such a basic device actually meant that there was less to go wrong - in this case, nothing.
And there isn't much else to say as the device worked continiously without any flaws until I replaced it over a year after being given a different mouse to try out. I've still got it and take it when I'm travelling. Although there are wires, I prefer the plug and go simplicty of it. Great little device.