Does what it says on the tin. Reasonable price and works the way it should. Delivery within a few days (3 or so, if I remember correctly).
I've read a review somewhere that mentioned that, with larger card sizes, the Sony Err phones take longer to play songs when you select them (though they play smoothly when going through an album or playlist). I've noticed a tiny lag but it's less than a second so no quarms, really.
The only thing I'd suggest is perhaps getting 8gb instead of 4. You can never have enough songs on your mp3 player!