Rating a game is always subjective since it's based on your own personal opinion and experience you've had playing it.
With that being said, I don't want to be biased but I'd give it a good 9/10. I still play Diablo 3 (the one with expansion) on my PS4 and it's such fun! I group up with my friends and try to push and complete high-level rifts. The consoles finally got the seasons added that the computer had for ages so there's so many new things to do - seasonal characters and so on. I'd really recommend it but that's just my own personal taste. I truly think it was/is worth its money.