First, let's talk about the best part of this manga: the art. Simply put, it's amazingly beautiful ...and anyone familiar with me knows I do not say that lightly. Even I can hardly find a flaw in it... it's just as it should be, each line in the ideal place... even the men, wonder of wonders, are drawn in an attractive way. What's more, Clamp manages this outstanding quality consistently, page after page, for eight whole volumes.
Okay, now the worst part: All that ecchi trash that was put in to jazz it up for the audiences susceptible to such things. It's just low. The worst part is that they even have the main character acting like a hypocrite, and they treat it like there's nothing wrong with that.
Hideki's got porn all over the place, and so clearly doesn't see anything wrong with looking at naked girls, but if someone wants to look at Chii naked, suddenly he thinks such behavior is very wrong. (Granted, Chii didn't want to be a stripper and was taken advantage of. But come on, he really thinks that none of the women in his porn have been taken advantage of either?) So a woman's privacy is only valuable if he personally knows that woman. And yet the authors often have the other characters calling him a nice and kind person! Also (this is more minor, but still), he goes and gets hammered drunk, and he doesn't seem to think there's anything wrong with that either. He should at least be ashamed... I think Clamp tried to make up for this and change his character to be less depraved with the end, since Hideki decides he loves Chii even though he'll never have sex with her, which is very sweet, but... it doesn't add up. He's still got all that porn lying around his room, and I'm not at all convinced that he's going to give it up, which is morally opposite his touching confession to Chii. If the story somehow sent the message of "well okay, he still has problems to work on" it would be much better, but instead they treat it like it's totally fine.
Having readers like and empathize with the main character is very important to a story, and shameless hypocrisy just isn't likeable... Clamp really missed the mark there. Also, good taste is essential for a good manga, and all that ecchi nonsense is the opposite of that.
The character of Chii, on the other hand, is quite another story. I think Clamp did a good job balancing a lot of things with her: she had to be ignorant like a child but not stupid, pensive but not a space cadet, tragic but not mopey, innocent but not shallow. I also thought the scenes where Chii read the storybooks were very sweet and just esoteric enough to add some nice flavor to the manga.
Next, about the message... for the real world which we live in, the message doesn't work... a machine, no matter how advanced, is only a machine... it's not a living thing, it doesn't have a soul, it's not a person, so it can't have a real love (sexual love) with a human being. However, the universe the story takes place in is not necessarily this one, so you can easily imagine it being a fantasy world where an inanimate object can be a person, and since a person is capable of love, then the idea works. If you adopt that idea, the series is much more enjoyable, because then you'll be able to appreciate the pathos of the concept the story explores.
Now, the plot. It isn't very dynamic--it's more along the lines of a slice-of-life manga, so those who prefer action or something fast-paced may not like Chobits. But in my opinion, it gets the job done. It probably could have been better, but it's functional.
Okay, so there are some very good and some very bad parts to this one, but all in all, I think I'd still recommend giving it a try. Even it turns out you hate the story, at least you got to see some beautiful drawings, right?