ITreviewed posted a review on the Skype 4.0 For Windows

Those who have been following the triple release of betas since last year won't see more than a few changes, but the free desktop VoIP communicator is a worthy final version that brings some key enhancements with video and audio bandwidth. In our tests audio quality and video streaming were excellent, although you should remember that quality depends on your Internet connection and hardware configuration. Using headphones that support ultra-wideband audio will also help. You'll never get the quality of TV, but there were certainly fewer jumps and sound syncing problems compared to previous versions of the software - that's thanks to the new bandwidth manager that salvages audio first as available bandwidth drops, followed by lowering the rate of frames per second and by compressing images more heavily. Skype 4.0 is a great product that makes VoIP easy.

Skype 4.0 For Windows Review