Having lost my previous macro adapter and expecting to have to pay more than this to replace it with something halfway decent, I was delighted to find this. Compared to the cost of a true macro lens, it's fabulous value for money. You maybe do need to know how to use one but when it do it adds a whole new dimension to your existing camera. It's especially great if you have a fixed lens camera with a thread, where you wouldn't otherwise have the option of macro.
The image through it is clear and sharp, with a good level of detail, a better option than close up filtres.
The only comment I'd have is with calling it a lens, which could be understood as meaning a proper lens for a DSLR. It's not, it is a lens adapter that screws onto your existing lens. But then you wouldn't expect to get a true macro lens for £20, would you?