Love
The HP and healing mechanics, especially Second Wind and Short Rests. Now characters don't need a magic-medic after every fight to move on with the adventure.
Hate: The core world as presented, and the horror of it being used in the various settings. I mean, FR had a cosmology and history why did it need to be folded into the core mold? This is one reason I don't want to see them do any other existing settings, their core assumptions and cosmology aren't that interesting to me.
Oh well, I had more Loves (or Likes really) but I don't want Mustrum to yell at me.