I noticed this webcam and it's probably Logitech's best value webcam. It's fairly cheap but the video quality is superb. There's a little bit of motion blur when things are speedy but I think it is easily ignored. The sound quality seems good enough that I've been able to throw my headset away and replace it with this.
It's a pretty standard webcam, it has a manual focus ring and Logitech's software packaged with it which allows you to add some effects to the video/images. Not too many but it can be amusing at first.
Anyway, I took a plunge a few months ago to test it (there weren't very many reviews around), and just recently bought my long-distance girlfriend one as a christmas gift as I'm so impressed with it. :3
If you go to youtube and search "logitech C300" you can see a couple of tests to evaluate the quality. The review from daanbrg is a pretty good example of how well the camera does.
EDIT: Now I want to mention how awesome Logitech is as a company. The C300 I bought kind of broke after a few months. Something seemed to happen to the wire which made it so my computers stopped recognising it. However, after talking to Logitech support, I got a replacement sent directly to me from the Netherlands (I live in the UK) without having to send my old one back to them at all. The information I supplied was enough. Thanks Logitech!