I liked it a lot. It's a riot of post-apocalyptic bloody zombie samurai steampunk, with spectacular violent action and some dark views of human nature. It's a laugh.
It's often compared with Attack on Titan, which is reasonable. Imagine a version of that show where the nearly mindless man-eating undead aren't enormous, but instead human-sized zombies with Spider-Man powers. They can leap through the air, shrug off heart-shots and punch dents in steel walls. (They're called kabane.) Apart from that, it's basically the same show. Mankind lives behind big walls and has undead-fighting elite combat squads. The people in power are scum. Our hero... okay, even the spoilers are similar.
That said, though, I think to some extent the similarities have been created by proximity. Those similarities are real, but it's not as if Attack on Titan was all that original to start with. It's a zombie post-apocalypse. They're just really big zombies.
Personally I see a difference in tone between the shows. Attack on Titan is more about doom and despair, at least in Season 1. Fighting back against the Titans feels so impossible that you assume they're all going to die. This show, on the other hand, is quite fun. It's a big, flamboyant action series with likeable heroes, a world of utter bastards and plenty of spectacularly imaginative undead monsters. The kabane are more than capable of tearing apart a city and eating everyone inside, but you'll almost look forward to their arrival because zombie-killing is fun.
The world is gorgeous. It's set in an alternate universe where samurai still rule Japan, with steam-powered guns and huge armoured steampunk trains. The latter are particularly cool. The shogunate's capital city looks stunning. Even the kabane are visually striking, since they're basically grey shambling corpses... but their chests are blazing as if their hearts were a wormhole to the sun.
Ikoma and his friends are likeable. Ikoma's a mechanic and a self-taught inventor with an occasionally dangerous lack of tact, but a powerful drive to do what's right. Mumei is awesome. Princess Ayame has no combat ability and a lack of confidence that basically causes a bloodbath when her leadership gets challenged, but she's willing to put her neck on the front line anyway and take tough decisions because she believes in them. Her courage almost feels greater than everyone else's, because she's physically weak. Meanwhile Kurusu is a trigger-happy, bloody-minded twat with the imagination of a pebble, but he can be exceedingly useful if you ever manage to hammer a speck of reality through his thick head.
The show's not afraid to let heroes make bad decisions. What happens in ep.4 is Ayame's fault, although lack of confidence is an understandable fault. Mumei's problem is overconfidence, on the other hand, and that can lead her into mistakes too. Mind you, neither even comes close to the selfishness, bigotry and all-round suicidal stupidity of... well, basically humanity as a whole, at least in this show. Oh, and the samurai are the kind of people who'll push around the little people and furiously pull a sword on you if challenged on it, while the shogun is the kind of ruler who'll kill an advisor for making a sensible suggestion. He doesn't want ordinary people knowing what's going on. "Excessive information causes needless fear."
Then there's Bibi. He changes the show's direction when he appears, which is fine. I liked him, but it has to be said that I was a bit vague on what he wanted and what he was up to. Do his actions make sense at all? I'm not sure, but: (a) I was basically okay with this, since the character retains enough mystery that trying and failing to read him could feel like character complexity and hidden depths, and (b) I think what we learn about his nature in the end goes a fair way towards justifying a lot of what we'd previously observed. "What will I destroy next?"
Is it realistic? No, but it's cool. Ep.12 is borderline ludicrous. (Didn't SPOILER ever run out of ammunition for that gun? The train moment, for the love of Mike, the train moment! You can reverse the SPOILER?) I'm also unclear on how SPOILER had seemed to do that mind-control on SPOILER a little earlier. I don't mind, though. The show's so full of verve and passion that for me it roars over those speed bumps. I got fond of the heroes, was impressed by the super-zombies and was given lots and lots of scum to hate. There's a second season promised for 2018 and I'm looking forward to it.