One Piece was one of the mangas/animes I hated the most around six months ago. I found the art/animation to be weird and I use to think how it could top the sales or how it was any better than Naruto. I was a real hater;it was the manga that I genuinely hated. I tried the anime and couldn't make it past the first episode. Then, one day, I decided to try the manga. At the first 10 chapters, I found the manga to not be as bad as I thought. At 30 chapters, I found it to be okay. At 60 chapters, I found it to be as interesting as part 1 Naruto. At 100 chapters or so, it became obvious to me who was a real OP hater that the manga is far better than anything I have seen and it deserved its popularity. OP arcs were better than Naruto's arcs. About the art, I found it to be really amazing. You have to get into OP to understand everything about it. In short, it is a well thought out story, with lots of character development, good fights and less talking, few plot holes, good and interesting story line which doesn't get repetitive even when reading 400 chapters at one go and foreshadowing. If you like adventure, you will like OP. I recommend you to get into it through the manga and and you won't regret it.
Try the manga. When I got into OP through the manga, I still couldn't watch the anime, even after reading 200 chapters. At chapter 500 or so, I got familiar with the series and the anime became enjoyable.