My D80 had a plastic film screen protector - similar to ones found on phones - that was coming lose. This clip on unit is much more secure and tough wearing, without affecting viewing angles of the screen. It covers the screen completely, though being plastic it does protude out slightly from the camera body, so if you're looking through the view finder for any length of time you can end up with fogging on the protector, but this is a very minor concern for making sure the screen is scratch proof.
If you regard it's prime task as keeping you screen free from dirt or scratches it works very well. Looks impresive, too. Considering you are viewing images you have already taken it's okay but not as clear as the D70's own screen. Clips on firmly and easily and looks good!
I've had the camera something like 6 years now, have always used the screen cover and thought it was pretty much indestructable. Not so, unfortunately. However this is the exact Nikon replacement part.