Hey @zombie
Yup! Syncing picks right back up! Basically, checks to see if any changes to files were made then syncs them. I shutdown my computer pretty often and have never had any issue with Dropbox picking up where it left off. If you are super concerned about currupted files or anything, just pause the sync before you turn it off (although my guess is Dropbox does this automatically during the shutdown process).
The only real concern would be if you unexpectedly lost power (for any critical systems though, I would always recommend a UPS), but even in that case, I still think you are fine.
