Before, I get started, allow me to say something: Hyped anime like these always seem to get at least one (usually many more) review where it is simply made up of "ermahgerd this anime wus so awesome u must watch it haz cool characters and fun plot" and a 9/10 or 10/10 on every section. I beseech you not to take any reviews like this seriously. Reviews should explain what makes the characters "cool" and why the plot is "fun." The ratings should be justified. If you just want to tell others how much you enjoy watching the anime, put it on your profile, or go find a forum, not a review site.
Attack on Titan is this year's Hype of the Year Anime, like Sword Art Online was last year. Fortunately, AoT proves to be more worthy of its hype than SAO. I'm not saying hype in itself is a bad thing. It's only bad when it is undeserved.
When I first saw the preview for Attack on Titan, to be honest, I was not at all intrugued. The premise was simple, and nothing really stood out. I did, eventually, give the show a try. After completing eight episodes, I found the show entertaining, yet I must say the pacing is all over the place. The initial episodes pass by very quickly, likely to get to the action. However, it is those action episodes that can sometimes feel slow, almost to the point of being dull. I didn't realize why until I reflected back on the episodes, and realized that other than a couple of events, all I could remember were people being crushed, torn apart, and eaten (or in other words, filler).
The first two episodes do a good job of introducing the feeling of terror that the characters must have felt. The problem is that dread seems like the only emotion anyone feels for almost the entire first cour. Simply put, the mood never seems to change. When you watch an action scene, you should be excited and anxious, not expecting ten more deaths.
Finally, I was hoping for more tactics and teamwork, rather than a typical shounen manga plot twist making the protagonist over-powered. Hopefully that doesn't spoil too much. They should have at the very least add some better foreshadowing to make it seem plausible.
The second half of the season improves its pacing and, to be honest, I have almost no complaints. The story is satisfactory and what I'd expect from a shounen type plot (I'm not saying it's predictable).
The sceneries and backgrounds are of average quality (nothing special). The facial expressions are where the animation shines. You can feel the emotions of intense expressions (I'll find some examples later). Also, action scenes are fluid and integrate cg animation very well (good examples in episode 5).
I couldn't help noticing that after the first few episodes, the titans began to look lamer.
Both opening themes are catchy and unique. The first song can be summed up as an "epic" feeling. The second starts off like some sort of parade song, then abruptly switches to a style similar (but different) to the first opening. Both use some german (not really good or bad; just thought I'd mention it). The voice acting is average, and sometimes, scenes (like the man in the scouting legion in the first episode) feel excessively dramatic. Sound effects were average (pounding noises when titans walked; noises of 3 dimensional movable gear sounded real). Background music was average at times, a little above average at others (usually the dramatic scenes).
Erin, the protagonist, is a typical shounen manga hero, who loves to charge straight into danger without thinking. He is easily driven by his emotions (typically anger). On a personal note, I hate him because he can be a huge jerk at times.
Attack on Titan features a large supporting cast (no, not as large as Bleach, but still more than the story can/should handle). I can name at least four named characters who have had such a small role so far, that they don't deserve names.
There is little character development. Erin and Mikasa have shown no signs of changing in any way. Erin never reflects on his experiences. He just thinks about what is going on in the present. Mikasa is only a couple steps below yandere status. Armin has some very subtle development, having improved wits and increased courage in later episodes. Jeanne (minor character) shows more signs of being affected by the events than anyone.
Most viewers, including mainstream anime fans, would likely enjoy this series. It's definitely worth checking out. If you don't think about the show too hard, you'll probably end up loving it.