This is, by far, my favorite action game on the PC. The game's magic system and its use in combat is fun. The difference in approach when you're playing the murderous Corvo versus pure stealth makes it high replayable. If only the game's story and pacing were better, it could have easily been among the best of all time.
I played Diablo 3 when it was first released. It was okay and after finishing the game, I ditched it.
A few weeks ago, Eternal Collection was on sale and a friend gave me a copy of it. Playing it now, the game does feel more fun. The mechanics are largely the same. This time, though, it feels more like Lord of Destruction. Not as dark but closer to how I remember the LoD.
There are several things to consider. Even with the updates, it's still an old game so it doesn't look as good as newer ARPGs.The campaign is just the 'tutorial mode', the real fun starts after you finish it. To get the full experience, buy the Eternal Collection.
If you're planning to get it. I don't recommend buying at full price; wait until it goes on sale.