Nekomonogatari - kuro is the last installment in the 'first' Monogatari series 'season' as Nisio Isin calls it. And with shiro part they are about development Hanekawa Tsubasa as a character. Stories of books are paired - first one marks Hanekawa's problems and second makes an attempt to fix them in some ways. In my opinion, Bakemonogatari - kuro is not as good in story department as second series books, so I rated it 8, but it is definitely better than Nisemonogatari. You still would see a lot of bras and pantsu, but they are part of main character of this story.
Art style, direction, and sound are just awesome. SHAFT studio knows its job and know it very well.
tl;dr If you liked Bakemonogatari this is a must, otherwise YMMV.
