Not agreeing with a character and not finding them likable does not equate to them being poorly written.
That said, this story has bigger flaws (only seeing bits and pieces of it) and it really should have been saved for when Steph was more firmly established in the new continuity. Because yes, while it's more than fine to write a character that isn't "endearing", it isn't doing her any favors when it comes to growing her fanbase.