They ruined him with the supergirl romance and having him jump to the future instead of enduring 1000 years in the phantom zone.
That 1000 years gave him a subdued and more mature aspect in the books.
Plus Saturn girl is a telepath not a telekinetic as in the show and she has a relation with a different character, while Mon-el is with a character called Shadow Lass. They’ve screwed the pooch on this one.
I will give them credit for a fairly decent Brainiac 5 though.