This is a fairly new offering from MS to take the pain out of synchronising files and folders. It doesn't seen to have had much publicity.
I have now set up several pairs of folders (one set held locally on laptop, the other lot on a remote server) to synchronise over a VPN connection and it is very fast (limited by the speed of the server at 'the other end'). Some of these folders are pretty big (>250 MB).
I have yet to play with the options other than 'Synchronize'.