Ben-To has a very strong opening. The first three episodes did a great job world building, setting the tone, developing likeable characters, and delivering on high-octane corner-market warfare. And those 3 episodes are arguably the only ones worth watching.
I suppose up to episode six, the show at least performs tolerably, but past that, the production falls apart.
The simplest way to explain: In the second half of the show, about 5 out of the 6 fights that occur aren't shown. Yup. They just don't show them. Including the finale fight that the last few episodes build up to (I guess they show about a quarter of the final fight, but not the part that matters).
For the most part it's just: "Lets do this! Yeah!"
Insert freeze frame of people charging, fade to black, show aftermath.
This is what most of the fights amount to in the second half, except for one.
Aside from that, the fanservice is completely over the top, and not even in a fun way. Believe me, I'm not one to complain about fanservice. Some people hate it, I think it's just fine. But in this show, it's so gratuitous and poorly done that it actually was uncomfortable. I just wanted to watch people fight in grocery stores. I don't want to see one of the characters forcibly give another a bath for 3 minutes straight of screen time.
Honestly if I was going off of the first three episodes only, I'd give this show a 9/10. It was funny, exciting, well animated, and well written.
After that, I imagine the production lead was like: "Yo... what are you guys doing? This is actually good. You're supposed to be shooting for a 5/10 rating with this show. No more fight scenes. Stop focusing on the interesting characters. Jam the screen full of tits. Where are the filler episodes? I got a fever, and the only prescription, is more filler!"
Overall: 5/10
Watch the first three episodes, then drop it. That's my recommendation.
