[CentOS] What are the advantages of upgrading from 5.6 to 6?

I've just installed CentOS 5.6. What would I get if I upgraded to 6? 
Would I have to reinstall all applications or could I just restore my 
/etc and /usr directories and do an update?

Thanks,
John

-- 
John J. Boyer; President, Chief Software Developer
Abilitiessoft, Inc.
http://www.abilitiessoft.com
Madison, Wisconsin USA
Developing software for people with disabilities