Finished the game twice on normal, first Barbarian and then Wizard. All in all the game is a disappointment for me.
At first glance it starts out strong with act I being very atmospheric and really long filled with nostalgia considering all the lore and characters (was really happy to see the butcher again).
The second act promises a lot being placed in the largest city of the Sanctuary, but never really capitalizes on it.
After that it all falls apart with two almost identical acts. It starts with teleporting you from one place to another with very little exposition on what is going on.
For a game 11 years in development it really seems sloppy and unpolished.
Not to mention how some characters stand out not belonging in this game. For instance Maghda an witch leading a satanic covenant is a very colorful character, flying on shoulder pads that are dragonflies, she would better fill a role as a storybook fairy godmother.
Not to mention what such a misplaced character does to the most iconic guy of the series.
As for the gameplay, well it's not as interesting as it was. Remember when you did a Zeal Pally and then made another one, now Elemental Avenger, and then another one Hammerdin? Well that part of re-playability is gone since every character lvl 60 is the same, you just rearrange stuff.
There were some weird decisions made with the streamlined skill system that scales with you and an even heavier emphasis on equipment. So now we have a monk that punches and rounhouse kicks with a damage determined by a two-handed battle axe, same goes for the other classes.
Mentioning streamlining, I don't know why the game is slower than D2, it's the only reason I can find for slowing the gameplay.
The two above mentioned problems make the endgame really boring, with advancement dependent hugely by gear which leads to constant grind and farming. Because of the scaling skill system your skill combo is of little use here without the gear to give you the needed DPS.
With all said I really don't see the game as the GOTY messiah every review tries to paint it.
For a game with 11 years of development, I do not understand how unfinished the skill/item system, story and overall presentation feels. Even features like PvP were cut in the last minute, the RMAH is delayed and a heap of technical difficulties for a 11 year cycle.
It's a good and fun game, but I somehow don't see the potential for longevity that it's predecessor had and expect to see player numbers falling fast after a few months.