Shirobako is basically a duty anime: no matter what you think of it, if you love anime, you must watch it. I knew it before I started, and haven't changed my opinion after 3 episodes. That said, it's pretty decent. The first episode was somewhat weak, in my opinion, but then the first episode of Manabi was weak too. Even the best of them need to find the groove. I noted "Shirobako is starting to pull me in" in 02, where Kinoshita, the director, had his turn to shine. He was shown to be an otaku, but with mature, professional fantasies, backed by the experience, and — critically — with a power to enact his fantasies (subject to the very real constraints of the real world, of course).
Another thing I picked upon in that sequence, is a contrast between the way Kinoshita sees anime and the way anime is seen at Anglophonic blogs generally, at least in my feedreader. We received a very good look because, as a director, Kinoshita had to translate his vision for his subordinates. On the blogs, anime tends to be reduced to sex. At the best, we get divisions between yuritards and normalfags. It's who fucks whom and the rest is icing. But Kinoshita's and Aoi's imaginations are far more sophisticated (they, by the plot, are on the same wavelength — but more about that later).
Overall, so far, the best parts are those demystifying the production process, because I don't feel much for the main character or her friends. She's a nice enough kid, but feels a bit too magical right away, and a bit too Miyazaki heroine. But the scenes from the trenches are priceless. The most stuck with me was the one in 03, where "Gothloli-sama" "checks" genga, while Ema observes. But there was much more, wall to wall almost. Somehow, the detail, the angle of the portrayal is satisfying where, for instance, Nozaki-kun and Denki-gai's wasn't (both of those deal with manga production). About the only time we saw anything in Nozaki was when Sakura and Hori were trying to apply shiage with comedic effects. Not so here. Shirobako is more like GA in this, except that it does its utmost to blend all the education into the action. It's exquisite. Too bad it has to be carried by a little cinderella princess, but hey... It's the anime we love. I'm looking forward to more of the same and have no regrets picking the not yet complete series thus far.
UPDATE: Omo adds the "later" thus:
It should not be surprising to see Kinoshita talk about Arupin’s core. What should be surprising is seeing the passion behind it.
 Among the most respectable blogs, Evirus is a standard-bearer of this trend. He's trying to do it ironically, as in "these two seem to be unable to keep their genitals off each other", but the result is what it is. Omo seems to trail, just to give you the idea of the spectrum. He was like that even before the 3DPD binge. As for the great unwashed, it's basically they want to be Evirus, but can't, and the best we get is the Metafap feature (which is great and all, but obviously focused).