As someone with an S7 , while many improvements are nice, they are cobbled by being buggy as hell.

If I just turn on power saving then turn it back off , I have to hard reset my phone because the resolution gets all messed up.

My android experience has been tarnished more by Google bugs than Samsung ones. Android 5 was a very buggy release, so much infrastructural change with little user benefit. IMHO Samsung should have skipped it entirely. I guess they bowed down to user and media pressure to always ship the latest android (although the media criticised them anyway for poor battery life, caused by Android 5).

I had a Moto G at the time with almost stock and Android 5 worked perfectly for me.

There were many many bugs, but this one had a significant effect on battery life: https://issuetracker.google.com/issues/37038331

For end users, it was a big regression from android 4, even if you personally found it "perfect".

Can you mention a few of those additional features?

Off the top of my head: Knox secure folder, better split screen options (app pairs), app suspension, power saving modes, file manager, better camera app, many more configuration options.

agreed 100%. it was not good before, but now? i prefer it.