Oh, Gonzo. Sometimes you can be so amazingly good, why aren't you always? Peacemaker Kurogane is everything I ever wanted from a historical action series. The character development is brilliant, and despite the Shonen character, it kept the wheee friends happy world to an absolute minimum, a minimum so low that it doesn't even register. As it is, the only screw-up Gonzo had was giving Sakamoto a 9mm gun in 1864 (and I remembered this year without googling. That's... a first).
But that's not the reason it's awesome.
The animation was the best I've seen in a long time (and that's saying something, considering I watch ongoing series). It's the first time I felt that 'pull' as if I'm almost getting sucked into the show, and I'll lose myself if I'm not careful, the sensation of disassociation from my body because my brain believes it's somewhere else - yes, the scene where the Shinsengumi stormed the loyalist meeting in the finale was THAT amazing. I vaguely remember screaming in Japanese and yelping at the monitor.
The music was very good. The two most memorable instances were the race in the beginning and the Shinsengumi marching to prevent the city from burning.
This isn't the reason it's awesome either, albeit it's a huge contributing factor..
The slashy undertones and HOT guy/guy interaction made the entire show very sexy. I'm sure I'm not the only one who saw how sensual the guys were with each other, right? Of course, I mean Okita with everyone (especially Hijikata), Okita 2 with his pimp, Suzu each time he was flustered (his blush was so cute!) and the cross dressing ninja who screamed sex with each movement.
And even though this gets near the reason it was as a whole HOT, it's not quite it.
It was HOT because - of the blood *sparkly eyes* serpentine movements, narrowed eyes, and blood splattering the faces and clothes of the guys who moved so very sensually among the cadavers they left behind. Okita 2 when he pushed his bloody finger to his pimp's forehead *drools* Okita EACH TIME HE FOUGHT was orgasmic. Suzu's daddy figure practically slithered around everyone else.
I swear this anime was an extended sex scene, start to finish.