Between the level cap being 60, the Paragon system getting completely reworked, all the changes to glyphs and itemization, and now two new classes on top of that, it feels like learning a completely different game from scratch. I ended up having to double-check a gearing and Paragon guide on Skycoach just to understand why my sorc wasn't generating resources the way it used to and what I was even supposed to do with the new item power system.
The gameplay loop itself is actually in a much better spot now, but Blizzard definitely needs to do a better job explaining all these massive reworks to returning players.