Ability scores cap at 30.
The way I read it was that they cap off at 18 for "normal" people, 20 for adventurers and 30 for monsters and divine beings. Page 173. That makes it easier to reach your peak, but sucks a little of the fun out of evolving an ability to a higher level.
BTW, did anyone see where spell level has any impact on saves? The only relevance I can find for spell level is if someone has some sort of protection up that shields from certain spell levels such as globe of invulnerability. Otherwise, it doesn't seem to matter. I only see spell DC as 8 + proficiency + modifier. If you can only max your stats as high as 20 (+5), then the way I interpret the new rules is that you couldn't have a DC greater than 19 (8+ max proficiency 6 + max ability modifier 5). There's something the fighter can take that allows STR to get as high as 24 (+7), but that's about it unless you're a god. It doesn't seem to matter whether you cast a cantrip or a 9th level spell.
From what I can see, there's no spell resistance either.
There's also some lax descriptions on some of the spells. For instance, Disintegrate describes what happens to a target on a failed save, but not on a successful save.
And another thing...have you noticed that Magic Missile no longer hits unerringly? It doesn't specifically say it doesn't, but nor does it say anywhere in the description that it does. Not cool.