The GUI looks the same to me.  The icon is different.  So far, I found the toolbar enhancements have changed by name and lets you adjust the small and large animations in the IE browser toolbar, "keep RAS connections after logoff" has been added to the logon controls, logon settings control added, a new category "Access Control" has been added, under "Task Bar and Start Menu" the option to not show the user name on the startup has been added, "explorer customizations" has been added (the number of folder customizations to remember), "Slide Show" settings (the adjustment of the number of milleseconds per picture) has been added, under "General", window size settings for using ALT-Tab added.
There's more I'm sure, but personally, I've already modified the registry to do what I want anyway and some of the things that IMO need to be added like Shell NO Roam/Bags and Bags MRU didn't make it (to keep your windows opening remembering details correctly everytime) still didn't make it.