I'm buying it mostly for Steph, but I'm also buying it because it's a Batman weekly AND it's Batman's 75th anniversary. I just wish Steph was playing a larger role. They hyped her role up so much but so far have failed to deliver. And James Tynion, who was so gung-ho on bringing her back, is doing the worst job of writing Steph and her story. I can only assume her role will expand in the second half of the series when she's in full-blown Spoiler mode.
As for a "dark, gritty" Stephanie Brown, it's too soon to say. She's so focused on taking down Cluemaster that we won't really see her true personality until this conflict is over.