I went over it once and as a longtime 3rd edition player and GM, I can say with confidence that 5th edition is 3rd editions with many of the small modfiers of combat removed.
My biggest complaint with 3rd edition was the wide gap of attack bonuses and saving throws over the levels, and this aspect has been adressed.
However, a very close second is it’s reliance on new class abilities at every level, which now in retrospective is a much more significant problem and antithesis to the oldschool style of playing RPGs. And in this regard Wizards remains true to itself and makes this the centerpiece of the game. Problems are solved by searching for the right special ability on the character sheet. And with this the whole business is completed. I don’t have any interest in running this game.
There are a few good ideas here and there, which should have been there 14 years ago, but it doesn’t affect the main structural problem I mentioned. I’ll probably keep an eye out for campaign sourcebooks, as in this regard 3rd edition did have a couple of gems. But the rules system is of no concern to me.