One of the subtle but much desired configuration options that was added to the Ubuntu System Settings for Unity in 14.04 LTS is the previously-covered support for locally integrated menus. Rather than having all application's menu bars be at the top of the screen with the global menu, through the System Settings you can have all the menus for each application be integrated back within their own window, similar to most other desktop environments. I certainly prefer the local menus, at least for my workflow, even when coming from former versions of Ubuntu Linux with the global menu.
Another seemingly small but much appreciated addition to Ubuntu 14.04 LTS is being able to easily configure Unity's launcher size, compared to its fixed size in past Ubuntu releases.
Another change for the Unity desktop in Ubuntu 14.04 LTS that makes it more usable with newer hardware (particularly high-density displays / laptops / ultrabooks) is the HiDPI improvements in Ubuntu 14.04 that make Unity work much better than other desktops. From the system settings area is a slider to easily adjust the UI scaling factor on a per-display basis (great for laptops when docking to a monitor in the office). The HiDPI support isn't perfect in my testing over the past few weeks, but better than when I was running Xfce and is at least usable.
Some other Ubuntu 14.04 LTS changes that I am enjoying outside of the settings realm and on the packaging side of things include the Linux 3.13 kernel for a still recent kernel release in this LTS release though Linux 3.14 would have been nicer for its newer features and support, KDE 4.13 made it in for those KDE fans, NGINX is in the main archive, and other welcomed package updates.
If you're currently using Ubuntu 14.04, what are you liking about it or not? Let us know within the forums.