The atmosphere, the tone, the mood of Cowboy Bebop is incredible. Taking elements from exploration sci-fi, western, and noir it creates a stunningly dark and slightly melancholic show perfectly in sync with the jazz pieces of the soundtrack. I feel a great sense of taste in everything while watching Cowboy Bebop. This while still having a great sense of humor which makes the show so enjoyable and not only focus on heavy psychological themes. I think the blending of the different genres and elements of western and japanese culture is perfectly balanced, thus creating something new which hasn't been seen before. The show was promoted by the producers by the motto "a new genre unto itself". It is naturally an exaggeration, but it does contain an element of truth. Instead of focusing totally on japanese drawn elements this show goes far beyond and creates an opera magnum which even Film as a medium has difficulties to achieve, being restricted in rules of the genres. Few directors have been able to transcend these limits and I believe Cowboy Bebop is considered a classic also for its ability to mix different elements coherently and beautifully.
But honestly I believe this is not enough to create a masterpiece. The CULT of this show is delivered by interesting combination of before contradictory or too-different elements while thematizing universal problems such as existentialism, loneliness, ethics. Friendship and relationship to other people is depicted in such great detail you surely will find something to see yourself into.
Long story short, Cowboy Bebop is not only style over substance. Thematic elements are incredibly deep and mature thus making it an unique experience. A classic.
