Likes:
6. 3rd edition adding the Sorcerer. I never played Wizard's/Magic Users under 1st and 2nd because I hated having to choose what spells to memorise and usually the wrong ones. Just having spell slots makes for a better caster in my mind.
Hear hear to this one - IMO all casters should work this way (and if that means concatenating a few caster classes together e.g. Sorcerer-Warlock-Wizard, that'd be a nice side benefit)
Dislikes:
3. Cutting off the game at about 11-12th level. D&D has always been about getting to that vaunted 20th level .....
Not always; only since 3e, which is where the 1-20 paradigm came in. Before that, depending on version it was either fully open-ended to as high as 100th or soft-capped around 9th-11th.
As for my own take:
Like:
--- the flatter power curve in 5e, as compared to 3e-4e
--- 4e's bloodied mechanic, which really wasn't followed up on in 5e like it could have been
--- rulings not rules ethos, as long as those rulings are consistent with themselves within the same campaign
--- degrees of success/failure, more evident in PF2 but D&D has kind of waved at the idea
--- PCs and NPCs using the same chassis in order to reflect that PCs are representative of their populations in the setting; 3e got this right but of course overdid it, then 4e and 5e abandoned such (so I guess this is a like and a dislike at the same time)
Dislike:
--- loss of separate sub-classes of arcane caster, most notably Illusionist and Necromancer, where the difference is in the spells they can cast rather than how they cast them
--- increased focus on being super-heroes out the gate (and then all the way through) rather than everyman-made-good or zero-to-hero or gritty survivalist games
--- any form of Ranger after 1e
--- decreased actual danger to the characters; the game used to have an overarching ideal of "get rich or die trying", and sadly somehow both the "get rich" and "die trying" elements have slowly faded away over time
--- the rise of the "character build" side of the game and the unnecessary complexity this adds to character generation; there's a lot to be said in favour of "roll some dice, choose a class and species, give it a name, and get it in play" char-gen.