Having played D&D 5e both as a player and dungeon master, I have developed an ambivalent opinion of the game. On the one hand, of the 5 major editions of D&D/AD&D, I believe 5e is the best designed and presented official version of D&D. While it is not a simple game, much of the game has been streamlined and the complexity that remains is both well-designed and, for players, digestible in small bites. This being said, I found it not fun.
I did not enjoy dungeon mastering D&D 5e. There were a number of factors involved:
I personally did not enjoy the extra time it took with the rules out of game to plan encounters, etc. That's just me. I would rather have spent my time on more creative aspects of the DMing. I am sure that with time, this aspect of the DM experience would have changed for the better.
Dungeon combat became both more complicated and less interesting with 5e. I quickly noticed that there was a blandness to encounters as every PC was able to take some sort of action almost every turn. Often, it didn't seem to matter what specific type of attack was used by the PCs. Each option seemed to have about the same chance of success/failure and did about the same amount of damage, whether melee, missile or spell attack. Lots of options every round for players but the effects of those options felt very generic from the DM perspective.
As a player, I simply did not enjoy playing it. As Mike Mearls and Rodney Thompson note in a presentation to International Game Developers Association, player feedback during playtesting indicated that players wanted fewer options and less complexity during combat but they wanted more complexity in the game outside of combat encounters (see the video below at about the 50 minute mark). The result is that D&D 5e offers streamlined combat (compared to 3e and 4e), but it offers the players plenty of character build options with every class at every level. I am not much into out-of-game character building, so this does not appeal to me. However, I can see where D&D 5e matches the sweet spot for lots of gamers.
