This pattern compares two descriptions and says the second is more accurate or appropriate. It's a way to correct or refine what you just said. The part before というより is what you're rejecting or downgrading; the part after is the better way to put it.

You can use it with verbs, adjectives, and nouns. For example, with a verb: 彼は歩いているというより、走っている (He's not so much walking as running). With an adjective: この部屋は広いというより、狭い (This room is more small than big). With a noun: 彼は学生というより、先生だ (He's more a teacher than a student).

In conversation, it often appears after a statement you want to adjust. It's natural and common in both speaking and writing, though in very casual speech you might hear just 'ってうより' as a shortened form, but that's informal.