Yes, UI is not changed from froyo or 2.2.1 because gingerbread is also topped with TouchWiz 3.0 that is why you see no difference in interface, but by upgrading to gingerbread you can see improved performance in multimedia, memory management, etc. The main difference is with kernel.. please look at the kernel version, it is not like froyo's. I checked youtube videos..now it is playing hq videos..
Upgrade to gingerbread without any hesitation and enjoy taste of gingerbread.