Zero no Tsukaima is an anime with incredible potential. What I mean by that is, if it dropped all the nonsense (fan service and repetition for instance) and focused on the story and such, it could have been amazing. It has some moments of clarity where it focuses on the story and the characters and when it does that, it is brilliant. (But it usually lasts just for a few minutes and that's a shame.)
Story:
Long story short, the story is basically about a boy who finds himself in another world, in this place no one speaks his language and he has no idea what's going on or how the got there. An accident gives him the ability to understand this strange language and he learns he has been summoned as a familiar to a mage and since most familiars are animals of some kind and a human familiar is (almost) unheard of, he is being threaded like an animal. By another accident he finds out being a familiar gives him special abilities. Basically an ability to use all weapons. So far so good right? Wrong, creators of the anime doesn't know a thing about storytelling. So usually the show is riddled by moments what a 10 year old would consider kinky and funny. This usually happens on every episode, several times. On top of that, this usually ruins whats supposed to be emotional moments. An act of heroism, an act of sacrifice, and boom, same nonsense about being funny and kinky. This is one of the rare shows that would benefit from a fan recut. Take out all the nonsense, rearrange some scenes and focus on the story a bit more. But I digress. As far as I understand, if the anime fallowed the original material properly, most of these issues would be resolved, but alas it didn't go that way.
Art:
Art is usually good overall. Colors can get a bit too bright or too dull at times, but thats to be expected. Not much bad, nothing groundbreaking, just fine.
Sound:
I wasn't able to find anything wrong with the sound other than some characters sounding annoying, so moving on.
Character:
How do I put this... Characters are fine but incredibly inconsistent. They seem to forget all about their past, their motivation and their abilities all the time. Also, there are many moments where character development gets abandoned simply to put forward the harem side of the anime. Which is especially stupid since the protagonist has already picked the main girl. Also, there is an issue with characters appearing once and being forgotten by the next episode. From what I gather, this is mostly do to anime not truly fallowing the original material where most of these issues not present.
Enjoyment:
You can actually enjoy this anime if you skip some of the terrible and annoying repetitive stuff. I tried watching it that way for the second time around and it really improved my enjoyment of it.
Overall:
This anime has great potential but fails to deliver because after a while it becomes incredibly repetitive. But if you have time to waste, it is a good enough anime to watch.
