By far the best iteration yet, IMO. AD&D will always have a special place in my heart because you never forget your first, but 5e is much closer to the Platonic ideal of D&D that I dreamed of back in the day.Heh, I must be the only one on ENWorld that likes 5e and thinks that it's the best iteration yet (aside from some nitpicks).
The main reason that it has been so successful is that it is really good! I'm not at all surprised that WotC are doubling down on it. When you have a winner, you stick with it.