Sengoku Musou is, originally, a series of games by Koei Tecmo, very known for its extreme Hack 'n' Slash features. The events of the Anime adaptation follow the fourth instalment of the game series and changes nothing of the original plot, instead enhancing some characters' traits and interactions. Also, a few 'original' characters are introduced, most consisting of relatives of already known characters.

You may think that, since it's a very cohesive replica of the original plot, the anime is at least decent, but that's not the case here, because the game itself does not have a marvelous story. All 'Musou' games are not known for their dramatical baggage or well-written characters, the interaction between characters is pretty standard and only works because it is not the only feature you get while playing it, the gameplay parts are way more engaging and most of the playerbase only cares for them, turning an anime adaptation into a pointless adaptation if not well developed.

I'm not familiar with the studio behind Sengoku Musou anime adaptation, but I can tell they are not the best technically for a lot of reasons. The animation is very poor, the drawing is not exactly bad but it lacks details, and even while trying to give some characters a more exaggerated personality, like most anime adaptations do, they still feel a bit bland. The battle segments are the best parts, but they are neither as engaging as other animes of the like nor as engaging as the experience of playing the original Sengoku Musou game. The most prominent 'original' character of the anime, Tokugawa Hidetada, has a generic design and very unfun jokes, being a big missed opportunity, and later this same persona/warrior would be depicted in a more interesting way in a spin-off game 'Sengoku Musou: Sanada Maru', making the anime version feel even more uninspiring.

One may think that this adaptation probably appeal to fans of the game series the most, like a 'fan service' take, but it's just such a mediocre depiction of the characters that watching it after playing it is way more pointless than the other way round. It's somewhat nice to see the warriors you love in a different media, some parts are fun, but it's not worth it the ride in the end. If you desperately want to consume Sengoku Musou content but cannot play the games, then I guess this anime adaptation fills the gap, otherwise I see no reason to watch it instead of playing it, especially subsequent to the release of 'Sengoku Musou: Sanada Maru', a story-focused spin-off game of Sengoku Musou 4, that does everything that this anime adaptation does, but extremely better.