Without a doubt, Ubuntu 16.04 is said to be the biggest and most significant release of the distro in years. In my opinion, the reason for this release’s perceived significance comes down to one thing – Ubuntu snap packages.
The idea (from the user’s perspective) behind snap packages is that Ubuntu enthusiasts can have access to the latest software packages without needing to worry about rushing to a new release of Ubuntu. Obviously, one must have 16.04 or higher going forward, but the general idea stands.