Review of Katanagatari

So I was at first unsure whether I liked Katanagatari enough to continue watching. I didn't like the characters' visual design (particularly the weird eyes), and almost every element of the setup seemed forced for the sake of the plot. However, there were clearly some mysteries to solve, and I got a glimpse of what might be a complex plot with many complicated relationships and histories between characters so I kept watching. Around episode 5 or 6 I decided I liked it enough that I would watch it to the end. I liked that the story didn't seem to show any sympathy for its characters (noplot armor, you don't know when a new character might die), and I liked the way that the main characters were developing.

As I got into the later episodes some things started to annoy me. I am going to remain vague here to avoid spoilers, but don't keep reading if you don't already know more or less how the second half of the story goes.
I realized that an entire group of characters touted as being dangerous and mysterious from the beginning... weren't. All they seemed to do was die. Sure they happened to be going up against really powerful people (except the times they weren't), but this was hardly developed as a plot point. This group had been humanized, at least partially, already. Why didn't they curse their bad fortune that they were being so annihilated? Why did no-one marvel at the fact that such a powerful group was reduced to almost nothing so quickly? The entire group ended up feeling like a waste of time and character creativity, adding nothing to the story. They were really only ever used to show other characters' strengths (by losing), but even that I found mostly unsuccessful because we never actually saw any of them being strong. I never even really felt that bad for them, because none of them ever really expressed an engaging emotion besides "I am sad that my friends are dead."

So then I watched the last episode. What. The. Fuck. One of the only (living) characters I cared about, and one that no small amount of time had gone into developing, was revealed to be a lie. The previous 12 episodes of character development were all essentially worthless. If that wasn't bad enough, the other character I cared about was completely reliant on the first. 12 episodes of gentle, subtle humanization turned into "I'm gonna kill things until I die because." Not something human like revenge, or insanity, or a drive to fix the broken world that caused such events, just "Eh, fuck it. May as well try to die." The remainder of the episode was spent destroying every goal achieved in every previous episode, while showing how meaningless each episode's struggle was because the MC couldn't use his full power.

In the end the swords may as well have been normal swords. Half of the character development of the entire show turned out to be only superficial. Roughly half of the remaining development was immediately regressed. About half the characters (many of which had cool designs/premises) ended up being completely meaningless. Plenty of the mysteries that hooked me in the beginning were poorly explained, requiring many assumptions to be made interesting in the end. Any feeling of grief or despair in the final episode was robbed by the story itself. Any feeling joy was rendered equally meaningless. The last episode made the whole story empty. Meaningless. I grieve not for the characters but for the story that was lost. So many narrative opportunities that I thought were going to be used in ways I didn't see coming fell by the wayside and weren't picked up again.

As for good things? Some of the characters are interesting, and all of them had a different feel. While the soundtrack wasn't really my style, some of the songs really gave the right atmosphere to a lot of scenes. Also the different ending songs were cool. The story was able to surprise me a few times by the direction it took and by which characters stuck around.

TL, DR: Watch Monogatari if you like weird and interesting characters, and enjoy a cliche-breaking disregard for those characters.
Don't watch Monogatari if you want to be able to finish it and look back at how far the story has come and how different thing are now. Because it doesn't come far. Don't watch if a story's missed opportunities make you just as depressed as a depressing story.