The story of the entire anime centers around a young man named Monkey D. Luffy who dreams of one day becoming the Pirate King, something he boasted about ten years before to the pirate captain Shanks who in turn gave Luffy his favorite straw hat and told him to return it some day when he became a great pirate. Luffy sets out to achieve his dream with literally nothing but the clothes on his back and, of course, his straw hat, but along the way he collects his nakama (his crewmates and friends) and a ship and sets sail determined to become the Pirate King. Each of Luffy's nakama have their own dreams and own goals but all of them are determined to do what they can to help Luffy accomplish his dream.
The arcs only get better as the anime progresses. Admittedly, One Piece doesn't really pick up until Luffy and his nakama reach the Grand Line which is around episode 63 or so (to conquer the Grand Line and find the treasure One Piece, which is on the final island, is what it takes to become the Pirate King). Once you hit the Alabasta arc though, things quickly pick up.
The arcs are, for the most part, absolutely wonderful. My favorite arcs to date are the Water 7/Enies Lobby arc and the War of the Best arc. I am also eagerly awaiting the next episode and all of the future arcs that are to come. I sincerely hope this anime continues for several more years (another ten years or so and I'd be satisfied xD).
I gave the animation a 7, because although the animation right now would be about an 8 or 9 we're talking overall animation, and the earlier episodes were poorly drawn and looked more like a cartoon (and a poorly drawn one at that). Over the last few years though, the animation has drastically improved and I am quite satisfied with it.
Like any long running anime there are always opening and closing songs that we like and that we dislike and for me it was no different. As for the voice acting ... the voice acting is superbly done with very few exceptions (there were, of course, some side characters that I didn't think their voices suited but I had no problem with any of the main characters).
One Piece is a very character oriented anime which is something I love. I hate anime with amazing storylines but no real depth to the characters. In One Piece's case they have good storylines with AMAZING characters. Luffy's Straw Hat Pirate crew is a very diverse group with their own personalities which keep us highly entertained. As of the current episodes the Straw Hats consist of a slighly naive/always hungry/great fighting/big hearted captain, an always napping/ill tempered swordsman with a horrible sense of direction, a sneaky gold seeking/map making/ navigator who doesnt take crap from anyone, a somewhat cowardly/ slightly naive sharpshooter/inventor, a lethal kicking/ lady loving / perverted/some-what ill tempered chef, a childish/slighly naive/easily duped/ big hearted doctor who loves being complimented but tries to act as if he doesn't, a quiet/calm archiologist who loves to make morbid comments and secretly loves the scary/creepy adventures that Luffy always sets off after, a soft hearted/loud/slightly perverted cyborg shipwright/inventor, and an undead/perverted skeleton of a musician. And those are just the main characters, there are also a lot of re-occuring characters who are just as interesting. Like I said ... the characters ARE the anime.
I was very skeptical when I first started One Piece and really didn't think that I would like it. In the end though, One Piece has become one of my all time favorite anime. One Piece is not for everyone, but if your willing to start something this long I give you the advise to try and stick it out because it DOES get better! I would recommend it to someone with a lot of time on their hands. I say this because once it picks up and you get hooked, you won't be able to stop watching ... it's almost like an addiction lol.