Mechanically, I believe that 5E is 3E stripped to the bone. It has all/most of the mechanical innovations of 3E, but with fewer options that are better balanced.
I do wish 5E was built in a way that allowed greater variety, but every time the designers attempt to open that door, the community shuts it. For example, having all characters gain subclass features at the same level (tested early in the development cycle for 5.5E) would have opened up a lot of design space. There's been a lot of great ideas left on the cutting room floor...
Outside of mechanics, 5E is its own thing. It's definitely shaped by the product plan, which offers up campaigns that are meant to be distinctly different from each other 1-2 times per year.
Despite a plethora of quibbles, it's a great game, my favorite edition of D&D by a wide margin.