Ellison is more of a “magical realism” dystopian author, like J.G. Ballard, than a “science fiction” author as most people today understand that term. (I recall reading that Ellison himself hated the label of science-fiction and resented being categorized as such.)
I like him a lot. “I Have No Mouth, And I Must Scream” is one of the most chilling stories I’ve ever read. He is really a genius at coming up with horrific scenarios, which is extremely impressive to me (being an extremely paranoid and anxious person, I’m very impressed when someone can outdo my own imagination.) He also has great titles.