Objectitly, Haifuri is not worthy of a 9. In no way.
The animation is not especially good, so is the music and backstory is just plain stupid, it did feel like the dumbest excuse imaginable to put schoolgirls on warships, it felt like Girls und panzer but even more poorly executed.
However this anime is more than the sum of its parts, I really enjoyed it like I enjoy very few animes.
I won’t spoil the story but characters do face high stakes like death, some bits are kind dark, it is question of treason, mutiny.
Yet despite that the anime go from serious to plainly stupid. “We face serious charges for mutiny, we may die because people are after us, oh yeah and now we are out of toilet paper, so let’s risk our life to get some” (no kidding, seriously it is part of an episode)
However, despite this, it is surprisingly enjoyable, and the marine battle are just plain epic, it has been written by people who clearly know their subject no simple kancolle of World of warship fans but true warship otaku.
Character development and relationship building between the girls if also quite enjoyable, little bit unoriginal and predictable but I still managed to like it and did grow fond of all the differents girls.
This anime is worth watching for the final episode alone, the final is just plain epic. I mean, for me it was final episode of a original gainax anime in term of epicness, action and emotion. The final was so right. And that is part of why I rate this anime so high. I really enjoyed myself with Haifuri.