If youre playing the game exclusively for its story, 5 Stars.
Anything else? Pick a different game. The monster scaling within the world system makes me feel like even though Im 50 levels higher than when I first started, I still take teh same amount of time to kill an enemy.
It does improve somewhat after you get into the higher difficulties, but even then there really isnt much to do. The game succeeded in bringing back the bleak sense of despair that D2 had but fell flat in the lack of things to do post storyline. There are 3 options. Helltides, which arent always active and also feel rather lack luster due to the lack of change in monster density from the normal map, Community events such as world bosses which really also feel like a waste of time because you spend 15 minutes standing around for the thing to spawn and then kill it in 30 seconds, and then nightmare dungeons which follow the same generic scheme over and over again. Its like an endless barrage of fetch quests except the only thing you have to look forward to is once again going back in to fetch the same thing.
Furthermore, the design on most dungeons is rather infuriating because i spend half the time back tracking to find the one little offshoot I missed in order to unlock a door so i can proceed forward. This is somewhat helped by endgame movement speed buffs from boots, but even still.
Lastly, the world is supposed to feel like one big open world experience, but really it feels like ride a horse simulator to get to where you need to go. Theres really no way to target farm loot unless youre doing the aspect dungeons. And since diablo at its core is about how much faster you can kill one thing, youre forced to complete the renown and statues of lillith to get just the smallest amount of damage increase.
As an aside: collecting 160 statues of lillith took me nearly 10 hours of playtime just riding around on a horse. Riveting. The renown system is only slightly better as after the main storyline every reagion was already in the second tab, but after that it took me roughly 5 hours to complete each zone.
Oh and you dont get the horse until your 2/3s of the way done with the game so I hope you like walking.