I've played and enjoyed every edition of DnD. 5e is my least favorite, because, like BPowell, I feel that many of the problems that plagued earlier editions have returned.
I understand why many people disliked 4e, but at least it attempted to solve some of the earlier problems. 5e is terribly imbalanced. A 2nd level Moon Druid can wreck a campaign (ridiculously overpowered), as can a 5th level Wizard with Fireball. The Ranger is so terrible they had to errata changes to it. There are many other things that have reverted back to their earlier, inferior forms, not because they were simpler or better, but to appeal to nostalgia. 4e for example had a simple rule, 'Attacker always rolls'. Now we're back to some attacks requiring saves from the defender, and others requiring rolls from the attacker. Now we have each class too almost having its own subsystems, with different rules for how they are handled. And yet the subclasses have very little complexity or diversity at all. Play a fighter once, and you've pretty much played them all. There are like 30 feats total or something like that; almost no customization at all. We're halfway through our second (short) campaign, and already getting bored. Items, especially magic items, are terrible. And the modules are horrible. Example: The module I'm currently playing has encounters like, '1d4 Hook Horrors'. Well, 1 Hook Horror would be a trivial boring fight, 2 would be relatively easy, 3 would be hard, and 4 would be a TPK. Do they really want me to just roll randomly for that? Terrible, terrible game design, as is clear from the reviews for the first module they released for the new system.
All of this means a game that is much harder for new players to learn. My players figured out 4e (even with the jargon) in a few sessions. My wife, who had a harder time with 3.5e, picked 4e up much more quickly. Now with 5e we're back to almost every class having its own subsystems and subrules. Yech.
And I would seriously doubt that the audience is back. Yes, 5e books sold well, but I strongly suspect that is because they are publishing something like 1/10th of the volume of products they published in 4e. At my local shop, there is literally like less than 10 5e products on the shelves altogether; Pathfinder has 3x the books or more. By this point in its life, 4e had multiple Players books, DM books and Monster Manuals. I would like to see some hard statistics that the 5e books are outselling all those combined. The fact that Wizards just laid off some of the staff (of 13 people) that work full-time on 5e doesn't bode well, and their lack of online tools (and revenue streams from them) suggests that the new edition is considerably less profitable than the old.
Opinions on these editions will vary, but my group much preferred 4e. We play a tactical, grid-based, combat-heavy, RP-lite game, and of course that is not for everyone. But for us, 4e was way more fun than the unbalanced, simplistic, and at this point downright boring 5e.