How and in what world in which 80% of Marvel movies exist was Black Panther "really bad"?
It was silly in bits, had a cliched hero arc, and generally wasn't bothered with the regular superhero showdown, but really bad?
Really bad is IM2 (and most of3), Thor 2 and 4, Spiderman Far from home, Black Widow etc etc. Really terrible films with almost no saving graces. BP was novel to a large extent in the portrayal of characters, and had solid performances all through. Not great, not even very good, just about par for the course.