I agree that W10 is a step backwards in many regards:
Pivots and controls on the bottom are the biggest ones that made windows phone, windows phone.
I can accept the loss of hubs/panoramas - but the hamburger menu is just awful and in the wrong place. (and Spartan url bar at the top).
One example that really annoys me is the the listen to music button is at the top of the screen, vs the bottom where its easier to just hit after pressing the search button.
W10 is an inconsistent mess in its current preview state, and the worst thing is that the new stuff is terrible.
The things which were positive that have stayed are the lock screen and start screen.
controls on the top of phones (especially as screens are getting larger) is a huge friggin mistake... do they not realize that most people use their phones one handed? Christ, just move controls to bottom for the phone os... and loss of pivots sounds awful