1) I like Paladins as a class. I think there have been enough niche power styles for paladins over the years that a class is appropriate (e.g. auras, challenges/sanction, & smites)
2) I like advantage/disadvantage. Not sure how this rule of thumb will work out in the long term, but we'll see.
3) Like several others, I'm not thrilled with humans getting +1 to every stat and another +1. (Although I actually toyed with the idea of giving humans +1 to each stat in 4e when every other race was getting +2 to 2 stats). My reasons for dislike:
* I have a fondness for 3-18 being the bounds of normal human abilities
* It would be nice for humans to be a true baseline race where you can roll your 3d6 x 6, choose a weapon and go. If you want to be non-human, then all ability score adjustment kicks in. So elves subtracting 1 from everything except dex would accomplish the same thing, but puts the (admittedly minimal) extra effort when you create a non-human.
* Why are NPC/monster non-humans (presumably) able to exceed human abilities but not PC non-humans ("presumably" because looking over the playtest bestiary, the highest strength monster is a minotaur at 19, which doesn't exceed human limits)?
* It seems really limiting to not be able to have a fantasy race of creatures that exceed human abilities in any single dimension.
I do like humans having an edge in the world, and I really love my human-centric parties, but there are other simple ways to do it.
* Give other races significant penalties or negative traits (e.g. elves have disadvantage against poison, or dwarves have disadvantage when attacking creatures more than 20' away)
* If they hadn't already given it to halflings, I'd suggest giving humans a mulligan once per encounter (which is probably one of the easiest things to explain to new players). Instead give halflings the ability to turn a disadvantage into an advantage or something a little more situational, complicated, and interesting.