Dark, Silent Hillish antagonist, real dramatic deaths, really funny at times, sciency.
Also, it gave birth to the queen of a certain fandom... so there's that.
The voice acting is really good. Many people try to immitate guilmon and fail.
I love the quote from Terriermon "moumentai". Which is the Cantonese akuna-matata.
To any adults who doubt an anime that is intended for younger viewers, watch Tamers.