I have played a lot of hours of beta so far but mostly just sorceress, but i would like to share my opinions as someone who dont like diablo 3 and love diablo 2.
World boss
I think this is great and its fun to fight them and other world events. I was honestly suprised by difficulty of Ashava as many people were getting one shot, me included.
Enviroment
Game looks great, some dungeons are really cool.
Achievements
Ehm i mean Challenges which is virtualy the same. I like that i get rewards for completing them which is better than simply achievement system in d3. What i dont like is how pop up thing looks. Its not very appeasing. In diablo 3 achievement pop up looks so much better. I liked that shiny thing with sound effect when you made one.
Gems
I dont like some of their effects. For example rubies, when you i use them i get only 5% life. Its almost nothing. I would rather see direct increase like +70 life. Actualy when i was using gems, i pretty much ignored anything except skull, ruby and topaz as didnt find any reason why use rest. And i certainly didnt need the rest. That brings me to resistances.
Resistances
I feel like they dont matter? I mean i dont even know what they do, i didnt feel like i have to check how much or which ones I have whole game. Not once. I dont even know when i should have some. In diablo 2 when you dont have certain resistances, you are dead and you hsve to choose equip to have them. In d4, i didnt have to. Their are even resist potions but idk when i should use which at all. I certainly didnt have to use them. And it made no difference.
Rings and amulets
Their stats are boring. Their need more different stats on them and wider range of stats also. Non unique ones i mean. Magic find, caster rate, attack rate +mana. I think i didnt see those for example
Monsters
I need more information about monsters, there are many resistances but idk which ones should i focus against which enemy. I think it would be cool to have monster catalogue where you discover their stats, abilities, resistances and which element their use as you kill them. Diablo 1 had similar thing.
Attributes
This is just as bad as it is in d3. There is zero player choice how to set your attributes. This limit diversity of builds and options how to evolve your character.
Item stats
I did pretty much everything in beta in term of content for 1 char, killed world boss multiple times, mychar is pretty much maxed with stats i think. And I still have no clue what ultimate, overpower damage or lucky hit is. Yes i didnt bother to investigate, but i think game should do better job to explain function of these stats. I have also hard time to understand some unique or skill powers. I have that sorc skill which summon cold blades and have some power which tells me something with cooldowns and i have yet to figure out what it does.
What worries me is that game have complex dmg mechanics and multiple resistances but not knowing anything about them seems to have no impact on gameplay. Its not like I was forced to care about resistances, to have more life or certain dmg effect on anything.
I dont especialy like itemization in d4. Its too similar to d3. And there its horrible.
Legendary items
I feel like Legendary items drops way too often so after while there isnot that excitement about them dropping. This will be even worse once you extract all their powers.
Skill system
I like skill tree and choices you make there. But i really hate that skills are capped at level 5 for leveling. Why? Also level increase on dmg skills feels rather weak.
Map
I think map should be more detailed, i for example discoveted some special chained chest and it was not on the map. I also certainly hate when you go to undiscovered map part, it gets revealed. This sucks because then you dont know which parts of that map part you searched and which not. Also small dungeons should have something once you search them. Judt like dungeons witch aspects change how they look on map.
Dungeons
They are kind of boring, they look nice but they all looks way too similar. Why have auto generated dungeons when generator makes maps which looks exactly same with just different directions.
Quests
I mostly like the quests but waiting period between something happens on screen is often way too long when you engage with events or npcs.
I think thats all for now. Generaly speaking I enjoyed beta and game play looks good. I am worried about itemizatiom and lack of character choices. Its way too similar to d3 which was pretty bad with this.