Overall the show was really great. I have some minor quibbles, but really they're just nitpicking. Probably the best show Ive seen since Fargo ended after season 3.
The only parts that irritated me are Blacktiorne constantly being saved/not executed for what seems like pretty much no reason at all. I'm sure this is explained more in the book, but the show makes him seem constantly hated by all sides (the Osaka crew, the Portuguese and even the (future) Shogunate) but for virtually no reason everyone has to pretend like he's a bargaining chip, or at least like his death would cause an issue, when it really seems like he isn't and it wouldn't. I mean I get that Mariko sort of protects him, and obviously hes the MC, but there are a lot of times where he should've just been killed. I mean he's not a novelty, he's not valuable (especially after they already have his cannons and "tactics"), and no one important really cares for him.
It does get a bit long at parts. I guess it's more of a romance/drama than I generally care for. I didn't need a 10 min tea scene where Mariko makes peace with her cuck husband. Karate Kid 2 did it better and in like 2 minutes.
Also I know it ends where the book ends, but I totally feel ripped off not having a big samurai battle at the end.
Still, by far the best show in years.