As a pro photographer I was getting increasingly frustrated with 'not having my full kit with me/the size of my full kit' so I bought a Panasonic LX5 as a 'go everywhere camera'. This adaptor allows you to fit a filter (either for protection or effect) in front of the lens.
Being able to use a polariser is a massive boon; and to be honest, if I had not been able to fit one I may well not have bought the camera.
The quality is excellent, but it could be all too easy to damage it by bumping against something or by sitting on it if it is a pocket. I would urge extreme caution here.
It works very, very well; and, like a Morris Minor, it is simple but very effective.