(disclaimer: long and jumpy review)
If you want to skip the long reading, here's my basic review of it "Rough start and awesome finish."
If you are not okay with gore, this is not your anime.
I started out with this anime unimpressed. I thought it was just a bunch of overloaded action (and to some extent it was a bit overdone in the beginning) but as the anime progressed I grew more and more intensely in love with it. Whenever I recommend it to people, I always tell them they just have to keep watching it because it gets better.
One thing I didn't like about the anime was when the arcs were held out for too long. I think if this show were marathoned though, it wouldn't really be a problem. By the time it gets into it's final arc though, (starting at the mission) it is handled better in that most of the episodes are amazing individually even if they are dragging out the arc. This wasn't exactly so before hand where you'd sit there and stare at the screen blank faced with disbelief that the anime with such amazing abilities has just yet again, given you another episode where nothing happens. However, as I said before, they do a better job of this later on in the series, and by that I mean, even when they aren't moving quickly to give you every bit of the juicy arc asap, they are making every episode up until the overall climax of the art, super amazing.
OH AND THE ANIMATION Oh my goodness, if you are a fan of watching beautiful animation then you have come to the right anime this is so so so so SO very well done. Sometimes I'd just rewatch certain clips or look for gifs of them online because I loved how well done they were (seriously, I did those things).
And if you like an anime that keeps the style of the manga, this is definitely your anime. At first I was a little put off by the style, but I very much like it now. (Especially when you see them older, I'm just saying)
Now the characterization is very interesting. I'm going to focus on the trio of the show for this. There's Eren who is an annoying shit (my personal opinion), but yet has some charm to him. He's interesting in that he's an earnest and stubborn character, but not in the adorable way, but in an angry way. He's all about revenge, which might make you think of Sasuke from Naruto from my little description right now, but honestly, it's not very much like that. Mostly because Eren is a little shit, but still. I kind of like Eren despite his super angry titan-killer self, and that might just be because he's kind of dumb-blind for it. He has little direction in anything but killing titans, just a lot of drive, and he has to work hard to be good at anything. He trusts his friends and works out his problems. He isn't afraid to take risks and tries to do what's right. I kind of like him (even though I still also kind of think he's annoying). His dark nature is more believable in the manga though, so I'd advise people to read the manga even though it's very similar to the anime (after you watch the anime though because it will make the manga so much easier to understand).
Mikasa is the girl in the trio and she is a bad ass. She's cold and doesn't talk unless she needs to. She's fine with fighting before speaking. I do find her also a little annoying (more so in the beginning), but I also respect her. I like her character a lot mostly because she isn't just a quiet badass, she's got a person in her. She's not just a two dimensional character, she has a bit of life to her. I think she's misunderstood a lot and people just assume she's a boring character without a lot of depth to her, but that's not true at all. I'm not just saying this because of what's happened to her, she herself, is an interesting character. She is a follower of Eren, but thinks for herself. She's protective of the ones she loves and trusts her friends (though she does know when to step in and tell them to straighten up). Although she's a genius, we're shown that she does have moments of weakness and still has much to learn (and not in the way where the character is defeated and has to work their way through rivals and stuff, but through the leadership and advice of her fellow soldiers).
Armin. MY FAVORITE CHARACTER (as well as Sasha) He is ONE OF THE MOST INTERESTING CHARACTERS because of the way he is introduced to the story. You think he's some weak push over but he's not. He is strong and independent, he is powerful and innovative. He doesn't realize this himself but is eventually beginning to see his own strengths (which he has always had). He's also curious and won't allow himself to be squished. Armin is interesting because he has a lot of weak points that he overpowers to become a better soldier. He's just awesome. I also love how well of a tactition he is, it's absolutely wonderful. There's a couple episodes that are mostly about him, especially this one episode that really explores him, and they're pretty damn good. Like on of the episodes was so good I just like... loved it better than some of the best action scenes. That's how much I love him. He's also stubborn and I like that he thinks for himself while considering others. He's observant and tries to understand whatever he can from the nonsense others see. He's definitely someone who you'd want to become king or something.
So yeah. I love that guy.
I don't know, I kind of find most of the characters annoying (besides Sasha I love her, and Armin) but I kind of like that. It makes it feel like the characters aren't for your enjoyment, they're there because that's who they are. It make them feel more real, more independent, and allows for exploration without allowing the viewers to interfere with their development. It just feels more honest that way. So, yeah I like that they're annoying because I feel like it makes the story itself better.
I really loved the anime by the end of it, so much so, that I read the manga as well and was super thirsty for the next season. It's ridiculously good and well worth watching. I just remember watching it in the beginning and think oh it's this type of anime, or that type of anime, an I kept on being proven that it wasn't exactly this or that. It's just really well done and complex.
OH COMPLEXITY HOW COULD I FORGET. This shit is so good, like the foreshadowing, oh my goodness, and the suspense, oh my goodness, like I just want all of the story right now so I can figure this shit out you have no idea. THERE ARE SUCH IMPORTANT THINGS NOT EXPLAINED THAT JUST LEAVE YOU SO READY FOR EVERYTHING THAT HAS YET TO COME. Especially if you are someone who loves details like I do. They keep on hinting at stuff and "approaching" stuff and then it's like lol nope. Do you know how much food they've dangled in front of me only to lead me into yet another trap of awesomeness to cover up their taunting illusions?! Oh they are so good at misdirection it nerves me! One of the major reasons I continue to watch this anime is because of the small things and because of the many things we do not know of yet. So good so good.
And the MUSIC holy shizam. I personally thought music was alright, but then the second ending was like, wow i really loved that so much. I did like most of the music anyway though. (I actually downloaded the soundtrack for the anime which I don't do often). I like the voice actors a lot too, they're pretty good.
Okay, so it sounds like I'm bashing this anime a bit, but I really do love it a lot. It's got such a great story and is wonderfully developed by the end of it. It's become one of my favorite animes where before I thought it was "Ehhhhh." Now it's just.... I JUST LOVE IT SO MUCH. Also, in the very last episode, I am telling you now, watch until the very last second or so help me we will have a problem. It is essential that you do so, understand? So yeah there's my very odd review of Attack on Titan. I hope you also fall in love with it!