The first thing you need to know about this program is it has a stupid amount of episodes (500+), and there is still a load more to come. If you are looking for an anime similar to the Dragon Ball franchise or Rurouni Kenshin, One Piece is probably the closest you're going to get.
Although the start is slow and also a little boring, once ironically heroic pirate Monkey D Luffy collects his crew the rapport is excellent and hilarious. The more time you invest into this anime the more satisfaction you will get from it.
When I think about the plot of One Piece, all I can say is it's very shonen. Don't let that deter you though, I mean it in a good way. Some people may find it a little repetitive, but that doesn't mean the series isn't entitled to the enormous following it has gathered since the initial release of the manga in 1997.
The art is fairly well animated albeit not in the traditional style that I like (the eyes). As the characters develop some of the battles are well drawn and great to watch. Overall, the whole feeling is very lighthearted. Don't try to take the One Piece plotline seriously, because it will let you down. Do watch a dozen episodes if you have the time, you could be a fanboy in no time.