I’ve played Diablo 1 and world of Warcraft which is slightly similar, but just tried d3 a week ago. I play most games on my switch, I grabbed the eternal edition a while back. The spec system looks really basic, but it gets fairly deep with runes and legendary items. What amazes me the most is the speed, there are a ton of graphical effects popping on high level gameplay, and zero slowdown even with 100+ enemies casting spells constantly. I’ve maxxed two characters so far and gearing them now.
D3 had a bad reputation at launch because it was a sequel to an all time classic and had very big shoes to fill, as well as RMAH, but it's an absolutely solid game now and yes, it is very well optimised