Despite (or perhaps due to) being a completely different vibe and style from the rest of the Monogatari series, this is hands down my favorite.
Very good arc here, all the good supernatural, psychological intrigue, with hardly any of the annoying ecchi aspect. Praise.
Was the Tsubasa Cat arc in Bakemonogatari not sexy enough for you? Here it is again but in lingerie. And I GUESS some more character development with Shinobu.
Too much inexcusable uncomfortable fan-service (read borderline illegal) to make the neat dialogue worth it. It is important to the overarching Monogatari story, so if you're embarking on it, muscle through.