I have a Samsung Galaxy A3 (2016) as a backup phone, getting it ready to replace my trustworthy but declining (app-wise) Lumia 735. The phone came with Android 6.0.1 installed and before I even bought last May, I was reading on various fora about an upcoming upgrade to Android 7.0 (Nougat). Even though I knew that the update would be nothing special, as an upgrade freak I was really looking forward to receiving the update. And it arrived, last week.
The update brought some nice visualization touches (e.g. the new top toolbar icons), some usability tweaks (e.g. organizing settings/options in a better way) and some noticeable lag to the phone. The latter is pretty annoying. It seems that it takes a couple of seconds now before I can enter the SIM PIN and unlock PIN, switching between open apps takes some time as well etc.; before the update, the phone seemed more responsive and quick to use.
I read that it is not easy to downgrade to 6.0.1 and that would validate the warranty; I am sure that it will be possible and I do not care about the warranty anyway. In any case, it still is a usable phone, with a great camera, lots of functionalities and great looks.
I guess that this is the price you pay if you are an upgrade maniac like myself…