Neonchameleon
Legend
4E is pretty much a complete mature system, besides fixing some of the math, and just bloating more powers for the later classes, I felt there was very little in terms of improvement because, AND THIS IS IMPORTANT, the playstyle was largely defined by the system/mechanics (at least a lot more than previous editions).
There was a vast improvement in 4e over the course of its lifetime. MM1 solos range from bad to terrible. Monster Vault solos rock hard.
Dornam I can only advise you take a closer look at the playtest material, especially the fighter to see the 4E influence within 5E. It's there, I assure you.
Firstly, if there are 4e influences on the fighter it's only because we 4e fans did everything short of staging a riot about the initial presentation of the fighter in the first playtest package. Because it was terrible. It was an even bigger disappointment than those seventeen individual rats in the Caves of Tapas. Combat Superiority I saw as Mearls' and co's understanding that we wouldn't accept completely bland, boring, and ineffectual nonsense served up under the guise of a fighter - but it still reminds me more of the 2e fighter than the 4e one.