Actually the most interesting parts of 4e's cosmology survived. Feywild? Check. Shadowfell? Check. Elemental Chaos? Check. The most interesting part that didn't make it is "Arcadia got invaded by demons", and that they can make that happen easily enough, although I am sure we will be inundated with "something actually happened on the outer planes, it messes up my homebrew" (as seen in the "Hey the demon lords actually did something" complaints from the Monster Manual and Volo's Guide) .
I did like the primal spirits and wish they got preserved as a druid/ranger thing.
Pre-4e eladrin vs. 4e eladrin: talk about a race to the bottom--super elves vs. super melodramatic elves. A 4e djinn made a better pre-4e eladrin then a pre-4e eladrin did.
4e angels did suffer from a little too much of "this is the angel version of X class", but previous edition's angels did the same except that X class was pretty much limited to clerics and paladins, so I will say that was a win for 4e (a book of Deities and Demigods with a bunch of templates for god-specific angel variants ["my Solar is different from your Solar"] would go a long way to improving that in 5e [and almost make up for the lack of celestials so far]).
I do have to laugh at anyone who thinks there is too much stuff in the outer planes in 5e, since almost all of that stuff was still there in 4e. Some of it was better (Hell and Archeron in particular, and the elemental chaos was better than the elemental planes and limbo, but since it is in the 5e's GW, I guess everyone wins). Let's take a look:
Mechanus: showed up around the time of Essentials (with a surprising backstory that I really liked)
Archeron: became Chernoggar, which I admit was an improvement
Hell: Still there
Gehenna: Just Tytherion by another name (although it does make sense that Tiamat was hanging out there)
The Grey Wastes: Pluton was basically the Wastes without the tourist trade of the Blood War
Carcini: Still there (just islands instead of a planet)
The Abyss: Still there. Hmmm--if demons were elementals, and we know elementals were in Dark Sun, does that mean demons were in Dark Sun?
Pandemonium: Still there
Limbo: doing the limbo in the Elemental Chaos
Ysgard: part of it moved to moved to Mt. Celestia with Kord (they needed to get those extra mountains from somewhere). The elementally parts fell into the Elemental Chaos.
Arborea: Split into Arvandor and Shom
Beastlands: Okay, lost that one.
Elysium: Well when Pelor shacked up with Erathis, I think they paved over Elysium to make Hestavar.
Bytopia: I am really surprised it didn't make into 4e, since the weird gravity when the two mountains met would have been neat with the 4e rules.
Celestia: Still there with 6 more mountains and 100% more Olympic games (because there wasn't enough evil to fight in 4e?)
Arcadia: as mentioned above, it got renamed and invaded (or maybe in the opposite order) by demons.