Superfluffic

Superfluffic (adj.): Lacking depth, intensity, or greatness; overly light, shallow, or trivial in nature.
Coined by Paul C. Okonkwo , originating from common usage since childhood to describe things that felt unimpressive or unimportant despite appearances.

"His argument sounded smart, but it was mostly superfluffic.”

“The book looked profound, but it turned out superfluffic and predictable.”