It's a "The gang comes back for one last project" kind of film. While the original series can drag at times, it did its job in establishing the important characters as well as provide an outlook on anime production as a whole. The movie on the other hand is a very very briskly paced affair on a now-troubled Musashino Animations and their struggles to get back on their feet for one last hurrah.
Mizushima's signature quick cuts (and military action) is here, and the pacing is very quick akin to Das Finale 1 or Kouya no Kotobuki Hikoutai, but it does help to string the story along without leaving a moment to spare. Of course as with those two one of the major setbacks is the lack of character as a result of the heightened pacing, which does hurt Shirobako more than the two seeing as by nature it is more of a Slice of Life Character-Driven show as opposed to an Action-Fest. At times I did find it hard to keep track on what's going on because it's been 7(!) years since I last watched Shirobako.
Still, it's really great to see everyone back again, and the film does have a nostalgic factor to it. Even minor characters like Funny Story Guy get a cameo in this and it makes me laugh every time. I do think it's a shame we didn't get an Initial D reference with the other production lady, but oh well.
There is some irony that the film's ending did feel a bit rushed, but even then it still doesn't diminish the value of the film as a whole. While not as good as other anime followup films, Shirobako is still a worthwhile watch. A great Slice of Life Working Comedy film is hard to come by, and Shirobako definitely fulfills that niche even after this many years.
7/10