*Contains major spoilers*
Well I'm about to do what most people consider suicide... Talk bad about One Piece...
Following: Full-fledged review and chibi review-version at the end for those who can't read:
To be clear about this: I have seen all movies and all the episodes released until now (ep 658) and while there are tons of things I'd like to talk about, one thing stands above all: One Piece never grew up like other shounen did. Naruto, Bleach, Dragonball and even Fairy Tail have become more mature and improved themselves over the passage of time. One Piece is still the same non-serious, immature nonsense that first aired in 1999.
Well to begin with One Piece's famous strongest point, the story... I am just not impressed. Ignoring the fact that after 600 episodes the anime's new arc revolves around talking toys and chibi fairies (childish as hell), most of One Piece's arcs are practically the same. Straw Hats arrive at said island, where a tragedy has been happening despite the place appearing bright on the outside, the whole tragedy originates from 1 man who is usually evil for the most pitiful of reasons, straw hats get seperated into 3-4 groups, straw hats kick villain ass, a big feast is thrown in by the glad citizens where another arc is foreshadowed before they move on to the next island. And while people will argue that the "War of the Best"arc was different, I still didn't find it the least bit interesting (2 deaths only? really?).
Staying on the story part, lets talk about what's arguably the most important story element in a shounen: The villain. One Piece has yet to show us a villain whose appearance isn't laughable. Crocodile was wearing a coat in the middle of the dessert, Enel's ears were too long not to notice, blackbeard is missing way too many teeth to be taken seriously, Donflamingo... I can't even begin to name the things that make him not-even-slightly threatening. In general One Piece follows the brilliant rule that "evil is stupid" and the protagonist's charge-ahead thoughtless moves always prevail against the plans the villains had been setting for a few good decades now. Going for villains' backstories, it's usually brilliant writing such as: Stupid for the Yolo, big misunderstanding in the past, pity jealousy and "we will explain it some time in the future". Sorry, its just hard to take these guys seriously.
Still on the story part: Being so kid-friendly is annoying. I can't get over how War of the Best, the "grand battle" of One Piece only had 2 victims, or how the Colosseum in the Dressrosa arc had no casualties whatsoever in a "battle to the death". Oda grow some balls and KILL people. Also regarding Ace's death in the War of the Best... I am not amused by how all of One Piece fans claim it as the most tragic thing to ever happen and yet we knew nothing about Ace other than the flashbacks. You could just as easily have put a Nazi Officer in his place and I'm sure the fanbase would still be crying buckets if we saw a flashback of said officer playing with the snow as a child while some uninspired dramatic music was playing. I can't decide if I'm more annoyed by the awful writing or how moronic the fanbase is.
Humor & Fanservice: Waaaaaay too repetitive. It was funny in the first 100 episodes, now I just want to chocke puppies every time Brook makes a skeleton joke or Luffy and Chopper get overly excited about something. On the fanservice + story part: There is no female lead. Nami and Robin became important characters for their respective arcs (Arlong + CP9) but right after that they slipped in the background and became minor characters. Still on the Fanservice part: Oh yeah, sex, flirting and even love don't exist in this universe. Everyone trying to take part in one of those is either a villain-in-disguise or someone about to be tricked because of their stupidity. In general: For One Piece Sex/flirt/love is stupid (right next to "evil is stupid").
Sound Part: 1st: The variety is a total disappointment. I can't remember a single track that actually got me on the edge of my sit. 2nd: The animators don't even make proper use of the soundtracks that already are avaliable to them. For example remember the final fight Luffy had against Crocodile. Do you remember the epic music? Obviously no because some moron decided that the fight shouldn't have music at all. Now imagine if at the same scene (final moments before Crocodile's defeat) One Piece's original opening "we are" was added. Suddenly the scene becomes 100% more exciting. They already had the copyrights, it's not like adding it would hurt anyone! The sound effects are equally terrible. Just look at the brilliant sound effect of Sanji repeatedly kicking Don Flamingo in ep 655... Sorry but I have made RPG Maker games with better sound effects than this. On the voice acting part: MOTHER OF ALL ATTROCITIES, IT'S HORRIBLE. Just look at the age of the voice actors, half of them are about to die (and I'm crossing my fingers). The voices are completely unfitting for most of the cast, not sounding at all like the age they're supposed to portray (well that's a big surprise...). Of course screams of despair, crying etc etc don't sound even relatively convincing.
Animation: Just awful. Way below the antagonism. The only worse animation example I can provide in a relatively similar episode release period was the "fast-paced-action" in the Naruto Vs Pain battle, and that was an artistic mistake on the studio's part that was never again repeated for exactly that reason. I won't even go into detail describing how lazy the studio is, using the same footage OVER AND OVER AND OVER.
Action: Doesn't really exist. One Piece doesn't ever show a proper fight without something goofy (aka annoying morons making even more annoying jokes) breaking up the seriousness. When the anime does decide to get serious it's just Luffy screaming on top of his lungs cliche lines while the villain doesn't even bother debating and just tries to kill Luffy (not that I blame them). The fights mostly consist of 10 seconds of action being repeatedly shown with slightly different soundtracks playing on the background each time and villain lengthy monologues inbetween them, usually followed by concentration-breaking flashbacks of things we have already seen a million times. If you're hoping for creative fast-paced excitement look elsewhere.
One Piece is like a kid that never grew up. After 600 episodes, despite all the "hardshps" our protagonist came through, he never really matured, none of the characters did. The tone of the anime didn't mature either. a graphics improvement and a gradual increase of the cast members being the only notable changes since the beginning of the anime and for me it has just become too monotonous, too boring. Once Piece is waaay past its due, but there is a single reason it stays alive. Nostalgia. People are willing to overlook all of its flows simply because it serves as a bridge for times when things were simpler for them (or so they remember at least). But if someone was to judge One Piece for what it really is and not for the happy memories of being taken by daddy to the Luna Park he would see it for what it is: Trash.
CHIBI REVIEW VERSION:
Aweful animation and soundtrack, followed a story that quite clearly follows a pattern even for its jokes, overly repetitive and with action that doesn't really remind of action. Immature, with annoying characters that are portrayed as "smart" rather than "morons" and laughable villains. Stay away.