Not necessarily worse... just different.
While Windows 8 will use the same basic kernel as Windows 7, it will be receiving Many Useful Updates
The perception of Windows 8 being 'worse' is all down to the new user interface.
While Windows 7's interface is the same familiar interface we have known since Windows 95, Windows 8 is introducing the Metro Interface
as the standard interface.
At the same time, they are removing several features from the classic desktop environment, notably the Start Menu and Aero interface.
Most who have tried Windows 8 complain that, while the new Metro interface is great for tablets, it is not as well optimized for classical desktop users.
I have unfortunately not yet tried the Windows 8 RC and am therefor unable to offer any personal incite into how the OS handles.
I would however expect that, after a short acclimation period, the Metro interface is just as usable as a pure classical desktop.