--Used With Samsung G600--
First off, if you're expecting quality (for £1.99!?), you're in the wrong place. However, that's not to say that this product is a bad buy - I'm not sure if spending an extra £1 for a similar adapter on amazon will get you anything different.
The adapter fits nicely in the mobile's socket. The short wire is enough to give you a bit more freedom in how you position the phone. The headphone jack, however, is a very tight fit depending on the headphones, and has a 'rough' finish. Overall, it gets the job done, even if it is rough around the edges.
(I did have a problem with bad sound quality the first time I reviewed these. However, it turns out this was the fault of the phone. If you're getting strange results, in the mp3 player, go to options, and change 'sound effects' to 'surround'.)