Re: 16.04 Long Term Support
I Intend to stick with 16.04 (with the mainstream Unity UI) until the next LTS. If you jump off the LTS track into the intermediate releases, then you either have to follow each subsequent release until the next LTS, or else somehow jump back to the previous LTS (not sure if you can do that without re-installing).
The changes to the Gnome derived "Software" program sound good, but I've been sticking with the original "Ubuntu Software Centre" anyway, which already does everything. The only thing which might temp me to upgrade to a non-LTS is if I wanted to develop "Snap" packages and needed the new functionality.
I've been very happy with Ubuntu. It's been steady incremental progress since the transition to Unity. The change to System-d turned out to be a non-issue, as Ubuntu delayed touching that until everything had settled down. I haven't noticed any change other than that System-d seems to take significantly longer to boot than Upstart did.
Unity itself has turned out to be a very good UI (the best of all the ones available for Linux in my opinion, and better than any version of Windows) and I don't think it needs any changes at this time when being used as a desktop keyboard and mouse UI.
The major development work in Ubuntu at this time seems to be focused on server, especially anything to do with "cloud". With phones taking a greater share of the client side, and with Android so massively dominating phones, that is probably a reasonable direction to take.