Blood+ is vampire anime with a solid mix of action and mystery.
However before you get into watching it, let me just warn you that unless you love a main character who is incredibly dumb, naive and a straight up wuss, you're better off watching something else.
Honestly, everything else this anime does great is dragged down by the incredibly unlikeable main character and even some of the supporting cast.
Saya is a main character with off the charts powers, but she decides it's better be a scared damsel in distress who gets manipulated by literally everybody because she's as naive as can be and without any sense of rationality. Episode after episode you want to say "do something you potato" but instead you're treated for another scene of her falling to her knees and randomly sobbing for no good reason.
Imagine if you find out you have superpowers. Super speed, super strength, can heal from any wound, and oh yeah, you need to get random blood transfusions every other day. Would that make you question something? Probably, yeah?
No Saya though. To her none of those things are ever worth asking any questions about. You'd think she'd be curious about all her superpowers, where they come from, what do they mean etc. But nope. She doesn't bother to ask a god damn thing, just does what some random creepy dudes she met 5 minutes ago tell her. Until she runs into a vampire who tells her a bunch of nonsense and she's like: "oh yeah, that's totally what it all means, I never cared to ask but now that you evil bloodsucking monster tell me some stuff I'll instantly believe everything"
It's mind blowingly absurd.
Her two brothers are no better. One who happily rushes off to kill himself for a stepsister he's known for a year, and the other who's primary reason for existing is to be a useless kid who drags everyone down. Like seriously, imagine you just ran into a vampire monster who ripped someone's head off and punches straight through walls and shrugs off bullets. Is your first reaction like: "I'mma go and beat the shit out of that thing with my bare hands and maybe a gun I can't really shoot"? Fuck no, that would be idiotic. Yet he keeps doing shit like that, constantly butting his head into everyone's business as if his 1-year of stepbrother relation is somehow grounds for being an annoyance to literally everybody.
It's just dumb.
Unlike many other shows, there's really no "connection" between the main characters either. You don't develop feelings for any of them. In fact, I spent most of the anime wishing they'd just kill them all off and introduce someone more competent. The characters just lack any in-depth personality and emotions. It's like you're watching animated cardboard figures.
I've seen anime develop a better emotional connections between family members within 10 minutes, than Blood+ does in 5 hours.
Failing in this regard removes a huge emotional impact from the show.
Art and sound are good. The overall story pretty good. But god damn if the main character and a large part of the cast just doesn't take most of the joy out of watching this anime.
Still, if you can tolerate poor characters, the rest of the show is good. Lots of blood, great action, mystery to figure out etc.