The crystal cover works very well at protecting the screen from scratches. Though, it's a “cover”, which means it doesn't enclose your PSP.

It attaches to your PSP four clips, which clip onto the silver elevated part which runs al a round the PSP. (Silver coloured for the piano black PSP's). Due to that part being slightly elevated. It's easy to use the interface, all keys can be easily accessed including the joystick. It doesn't interfere with any of the inputs such as the USB, headphones, UMD drive etc.

The only problem I have with it, is that i get worried that it will come off easily with such a small elevation to attach to, though it wont come off during normal play and you have to put some effort to pry it off when taking it off, (from most positions).

So if you want to protect your screen for just chucking in your pocket and forgetting your keys are there, this is good, but if you are a person who keeps dropping your PSP, choose the case.