Smart stories, intelligent subject matter(stuff that won't insult my intelligence... the 'Love Hina' syndrome), stylish characterization, witty yet sly heroes and villains. You know something that could possibly ape Bebop I guess. I am in that kinda mood.
I think One Piece kind of transcends its intended age group. Its exterior is very shonen, which means powerful characters and a lot of fighting with an emphasis on friendship and being brave and whatnot. Underneath, though, there's a helluva lot of charm and some well-built characterizations. Would I call it smart? Its not really something that requires a brain to understand, but its not mind-numbingly retarded either. There's some legitimate drama and the grand scale of things really emphasizes a higher level of engagement in the plots and characters.
Intelligent subject matter? Intelligent enough, I'd say. The characters definitely deal with some complex issues and interesting conflicts. The current fansubbed story arc, Arabasta, centers around a princess trying to stop a revolt within her kingdom which is suffering from a combination of distrust in their king and a serious drought. This is all being aggrivated by a mysterious individual basically pulling some underhanded shit to stir the pot and turn the kingdom into his own utopia. This is intertwined with a number of other underlying threads that I'd rather not spoil should you choose to get into the series. So the stories do not just center around "RAWWRRR!!! I'M THE STRONGEST!!!! LET'S FIGHT!!!" There is some real emotional complexity invested in them.
And best of all, there's almost ZERO fanservice in OP. So no Love Hina syndrome.
As for stylish characters? Got em in SPADES. Just about every character Oda (he created One Piece) comes up with is totally unique. You're not going to see endless numbers of spiky-haired clones here. Oda's sense od style is totally his own and he's definitely one of the more unique artists working in the manga/anime biz.
Witty and sly characters? Plenty of those, too.
I would love to say you'd like it, as most people who pick it up get hooked, but who really knows until you actually look into it? The only thing to watch out for is that the first few episodes aren't THAT great and while the first couple arcs are entertaining enough, people will tell you that the series doesn't really get going until the Arlong Arc which is about 30-40 episodes in. It may seem silly to say that, but One Piece is a long series without an end in sight right now. So when all is said and done, Episode 40 or so is still pretty early on.
Edit: I forgot to explain the premise. Basically the greatest pirate who ever lived, Gold Roger (or Gol D. Roger depending on who you ask
) has been captured and executed. Before he dies, he makes known that his greatest treasure, the One Piece, lies in the Grand Line. This sets off the great Age of Piracy where people from all over the world are attempting to find the One Piece. The main character, Luffy D. Monkey, is rescued from a sea monster by a pirate named Shanks whose crew regularly stops in his town. Shanks loses an arm in the process and before leaving port, gives Luffy his straw hat telling him to return it to him someday when he becomes the pirate king. So, basically, when the simple-minded Luffy gets older, he decides that he's going to become King of the Pirates and find the One Piece. Seeing that he idolized Shanks as a kid, he ate the Gum Gum Fruit in an attempt to gain his respect. The Gum Gum Fruit is one of a number of different objects called "Devil Fruits" that appear throughout the series which endow whoever eats them with a certain power at the cost of their ability to swim (obviously, this can be a problem in a water-dominant society). Luffy's power is his ability to stretch like rubber. What basically ensues is a grand adventure as he travels the world finding crew members, encountering trouble, gaining a reputation, and hopefully, ultimately finding the One Piece and becoming the Pirate King.
