It's a silly gag show, based on a four-panel gag manga. However it's also the most detailed, compelling portrayal of the Warring States era I've seen in anime. It's even a bit funny, sometimes.
It's not even covering much of Nobunaga's life and (bloody) achievements. (This is Season 3, though, and there's more in Seasons 1-2.) We're seeing 1570-71 and not even all of that. We don't reach Nobunaga's atrocities in October 1571, for instance. What we get instead is a detailed picture of all the politics, individuals, battles and shifting allegiances. This is surprisingly cool. I dislike samurai, but this is a well-told historical epic. Everyone's a goofy cartoon version of themselves, but that's okay and makes it a lot more fun to watch.
The show's heroine is Chidori. She's a tiny, adorable ninja with an outrageous body count and a bit of well-hidden guilt about that. She reveres Nobunaga and always improves the show, but unfortunately doesn't get much to do because she wasn't a real historical figure.
As a comedy, it's fairly moderate. I worship Akitaro Daichi, but this isn't his funniest work. I'm sure it would work better if I knew the period and people, though.
I started watching. It seemed sort of okay. At that point, I was still watching it as a not-that-great comedy (although it has some good jokes). Gradually, though, I realised that I was getting interested in the story. There's some quietly deep material about the split loyalties of a daimyo's wife in this era (since her husband might easily be going to battle against her brother) and the things they can't say to a samurai. There's lots of fighting and blood. A hero dies impressively. The tone is light, but we're still seeing bloodbaths. We learn that Chidori's been prepared to die for a long time.
This show is better than it looks. It can be funny, but it's also educational and surreptitiously epic. It's definitely the best anime portrayal I've seen of these historical events. It's even marathonable, of all things, which you wouldn't expect of a four-minute gag anime.