Favors has a decent jumper and good low post moves, something Rudy still has not developed, and in fact, before his injuries was talking about developing a 3-point shot.
He does have a decent jumper. Good enough to hit wide open, not serious enough to commit guarding.
He is serviceable in the post. Unfortunately, spacing is nearly as important as skill in the post (which the Jazz will be seriously lacking for much of the time Favors is on the court) and it's just inefficient/bad basketball most of the time.
Having both he and Gobert on the floor is a net negative offensively.