My experience with ARPG's is limited to diablo 3 primarily, but I spend a lot of time gaming, mostly mmo's so still character building.
Diablo 4
Pro's
-Great cinematics
-Skill visual effects are pretty cool
- Added depth for late game with paragon board
-Easy to form a party and play with friends
-Feels good crushing mobs now that mob density has been fixed.
Cons
-Poor story telling. No character back story. I disagreed with the decisions made in the story but my character was just along for the ride for some reason. I'm not a nephalem like diablo 3 so why am I so strong?
-Horrible loot drops. This was a recurring theme through the whole game. Poor drop rates of good gear and later in the game it mostly comes with poor armor ratings or the lowest sub stat rolls.
- Blizzard has send out tonnes of nerfs since the beginning of the game, personally i have levelled a druid and a sorc past the campaign to a fairly high level and they dont feel good. I want to feel strong but you have to stick with very specific builds.
-Vulnerable damage is king. Using a build without it is a bad experience.
-I found druid to be very unique reliant, I managed to end up getting things to make a werebear build but now that I am almost level 90 I want to try werewolf. Well too bad for me unless I get a specific helmet. Instead I get the other unique helmet (7 times and counting)
-World events in world tier 4 are boring because level 100's can solo the bosses and mobs before melee classes can reach them
-There is no real end game. Seasons wont fix this, it just means once casual players are reaching the point where they realize there is no end game there is a new season to start levelling all over.
If you've made it this far I will say-- If you can get the game on sale, go for it. I wouldnt pay full price for it. I got it as a gift.