I noticed on Linux Mint that the Dropbox icons and menu options don't appear in my Dropbox directory. I did a little research and this is because by default when you install Dropbox it'll assume you're using Nautilus as your file browser, but by default Linux Mint uses Nemo (which is a fork of Nautilus).
Luckily it's an easy fix:
sudo apt-get install nemo-dropbox
Then quit all running instances of Nemo:
When you open up your Dropbox directory again you'll see the familiar Dropbox icons.