Campbell
Relaxed Intensity
5E uses a lot of 4E mech itanics to duplicate pre 3E playstyles probably more like 2E.
Mechanically there's not that much wrong with 4E it's class design specifically powers and it's playstyle.
4E was good at being an advanced minis skirmish game. Wasn't so good at everything else.
It was really good at heroic fantasy. With strong scene framing and good handle on skill challenges it could be used to play out some really epic fantasy. This really plays out well with the thematic material attached to Paragon Paths and Epic Destinies.
It was horrible at dungeon crawling and conflict neutral play. Unfortunately they decided to make almost all the official adventures dungeon crawls.
It was really good at being what it was. It was really bad at being Dungeons and Dragons.