The story is simple. It's somewhat drowned on most of the time. The fighting is ok and very entertaining to watch at times. On the other hand, the action is bad compared to other animes. The most stupid thing is how Luffy just random pulls power out of nowhere when needed -.-. Let him lose properly, let us see him gain strength, not just randomly give him magic powers in the next episode. Hunter x Hunter is a great example of showing to the audience how Gon gained his strength.
Overall the let-down is in between the start of the arc to the end (meaning pretty much the whole story). During these times one piece finds a way to add lousy speech, action and can add cheesy sad story to make the audience try to relate to it, just doesn't work. For this reason I am giving the story 4/10
Animation & Sound:
One Piece animation is unique and can draw you in. The arts get better and better as the story progress. It's the same story with sound. However you would expect the success of one piece would let it improve the animation standard to 2013/2014. It still lacks quality compared to animation that came years before now. For this reason I am giving both of them 5/10
One Piece universe has a wide a wide range of characters. The main crew is fun to watch but also can be annoying at times. The downside is newer characters are just not getting there screen time worth. We don't want to wait another 100 episode to find another fact about them. Well I guess they done it to drown the anime on. Another downside to characters I would say is the villains for Zoro. I mean come on! One of the biggest badass in the anime yet they can't even be bothered to create a more interesting character without a cheesy or disinteresting story to fight him. Overall I give it 5/10 for the poor background information on the characters we are given.
Overall, if this is the first anime you chose to watch, you might enjoy. If you have seen other animes that set the bar high, such as FMA, then you will be disappoint. The newer arcs just feels like Oda is doing his best to try and rake in money rather than continuing putting soul into the anime.
However I would say that it can be enjoyable for a younger audience or someone who is new to the anime world.
Overall rating for the anime: 5.2/10