The real quality that makes this anime an instant favorite of mine is the way in which it asks questions; questions about trust, questions about who we are, questions about what made us the way we are. These questions are not something most shows push for.
The anime starts out pretty slow and the English voice acting may be bad but somehow becomes more comfortable in time. The animation is a little dated but still surprisingly good in some parts (especially later on).
The music is soft, lots of piano and violins. Later in the series classical music is incorporated and it is a gloriously majestic addition to the anime.
The characters will undergo much more growth than many shows (in my opinion) and even though it may seem confusing it is always possible to find truth hidden throughout. The parts that get confusing get more explanation in the later movies although don't expect to walk away understanding everything, this anime wants you to think, HARD. I believe that it is entirely worth it, this anime has managed to do something extremely rare and in the process revealed a lot of truth about life and how we all learn to live and love ourselves.
This anime deserves to be a classic and deserves to influence people which I know that it has. This anime is not for those looking for something lighthearted, this anime is thick, complex, layered, truthful, harsh, and everything I am happy to see reach a mainstream audience. One of the best things ever.