Ubuntu 17.04 (Zesty Zapus) Available For Download
The new version brings updated applications and various under-the-hood improvements, along with bug fixes. As expected, Compiz and Unity have only received minor improvements and bug fixes.
On the other hand, Ubuntu 17.04 includes the GNOME 3.24 stack for the most part (GTK3 along with Totem, Disks, Calendar, and so on). There are some missing bits, but this is still pretty important, as Ubuntu didn't use the latest GNOME since around Ubuntu 11.10 / GNOME 3.2.