I discovered anime and consequently manga in 2007. I started with Naruto, which is fairly popular worldwide, and gradually moved to more esoteric anime and manga. Cartoons and comics, I had known of since I was a kid, but here was something different. With cartoons (and comics), there is always the perception that they are for kids, and while the perception is not true in some cases, Simpsons and South Park come to mind, it is mostly true. The target audience for most cartoons are kids and young teens at most. Anime (and manga) on the other hand start with young teens and continue on to mature adults as their audience. The themes that they are drawn on are much more varied as well, who would ever think about publishing a comic book about a pianist or a school teacher? But with manga they do that and more in all seriousness. Moreover, even the most generic manga dares to ask troubling, profound questions, and takes time to deal with them: when I first watched it I was astonished to see serious existential questions being debated in Naruto, a manga considered very average by manga esoterics (Naruto is a manga that was made into an anime, I watched the anime first, then read the manga).
Before anime, animation for me was just for entertainment, I did not attach any particular artistic significance to it. But, with anime I started seeing it differently, I realised that it was art in motion. That with animation one could think on things, one could portray things that just can not be captured on film. The human body is inadequate, space and time as we can capture it on film are inadequate to portray the thought, the emotion that asks to be shown: in animation one transcends these boundaries. Metaphors can be made visual, the bleeding heart of the lover shown. I put forward Neon Genesis Evangelion (the anime) as a case in point: the psychological struggle the characters go through can only be depicted through animation; it can be talked about on film, but the psychological turmoil itself can not be captured on film, animation is the right medium for it.
Films that use excessive animation bore me, why not just make a fully animated film instead, what is point of using human beings as props in the midst of all that animation? I am not against using animation in film however, only against using it to the point where the humans artists start to look out of place.