We recently got Sharepoint 2013. Our users run Office 2010 and IE9. Especially latter gave us problems because of the missing drag and drop functionality which is HTML5 thus not working for IE9.
A colleague of mine found a solution in running SP in "2010 mode" which uses WebDAV rather than HTML5 for the drag and drop upload feature.
Now my question: If we run in "2010 mode" ,do we lose any 2013 functionality? What is the difference beside the (uglier) User Interface?
PS: I know how to get the drag/drop into IE9, i.e. by installing SP Designer 2013 and then Office SP to re-enable the opening of files but its quite a hassle to apply on users machines.