I'm...*sniff*...speechless. I'm not sure what to really say! The animation is gorgeous, the characters are deep and interesting, the story has some really nice plot twists, the music and voices are fantastic (in Japanese...of course), and the ending really hits the mark.
Perhaps the closest comparison I can make (and it's still a fairly loose association) is to a modern re-telling of Pinocchio. No, it's not the same story...but you'll understand why I say that when you watch it.
I think what I love most about this series is the lessons it teaches about love, sacrifice, and what it really means to be human. It's definitely not a series for kids. Although nothing truly graphic happens, there are a few ecchi moments that some (American) parents would definitely object to. We have a much stricter culture here about such things...but I digress.
I found I really connected with Hideki. He reminds me a lot of myself in many ways...although I have MUCH better control over myself in public. ;p
I've found that the stories that stick with me the most are the ones that really make you think. If you allow yourself to become immersed in the world and the characters, you come out of it with a new appreciation for other perspectives. Even if you, in the end, don't agree with the philosophies explored, one can at least have the understanding of why they might think that way. Chobits definitely fits into this category. I'll be picking up the manga next! I hear it's even BETTER!
On a side note...SUMOMO ROCKS! I WANT ONE! LOL!!!!! (Come on, Sony...I know you've got a beta one in the works! Sign me up!!!!) -> watch the series to understand