At first you think that One Piece is a typical Shonen with ridiculous fights and shitty drawing. In fact, these two never improve. But there are things that make One Piece soooooo... much better than Bleach, Naruto and even Hunter x Hunter. And these things are the story, characters, foreshadowing and the unique One Piece universe. There are also nice concepts about will inheritance, man's dreams and giving up personal goals for the sake of close friends/relatives.

Ok. So here are my scores:

Art: 0/10
Music: 0/10
Fights: 0/10
World design: 0/10
Characters: 10/10
Story: 50/10

So Overall: 60/60. Deal with it.

The problem with One Piece is that you need to understand all these foreshadowings, concepts and not complain about PIS's (Plot Induced Stupidities) which can be quiet difficult. So there will be a problem if you are mature enough to see all the stupid and ridiculous things but not mature enough to enjoy the good things.

P.S.
Sorry for the bad english.