They really have been pushing that whole "From the mind of Tim Burton" thing, haven't they? There's a lot of Burton here though, Gough & Millar wanted him from the start and to create a work at least in the aesthetic of Burton. Burton did directly design the main creature, and I'm sure it's no coincidence that Danny Elfman is doing the music. The stagy scarring on Thing seems like an homage to Frankenweenie and so on. His experience with animation probably explains why Thing is so effectively presented, even though a human actor is used for most shots I think he understands how to make such a character work. So I think we can attribute a lot of the style of the show to Burton but the story appears to sit firmly with Gough & Millar but I think it was a collaborative effort to be sure.
Yeah -- Burton does the things Burton does, which is direction and style and design and music. But as you say, this series project originated with G&M, and they brought in Burton afterward (although he had been attached to a couple of earlier film versions -- I would've liked to see the cancelled stop-motion one). So it's no surprise if the writing and storytelling are less "Burtonesque" than the visuals and direction.