I think Studio Pierrot has done other shonen titles, including the anime of Yu Yu Hakusho. So it's true that QUALITY is more or less 90% of the time, but then there are the sakuga episodes! I thought that was pretty decent adaptation.
One Piece never has any sakuga moments. Never (unless there has been one recently). The only thing that comes close is movie 6, oh my god animation orgasm. Don't get me wrong though, I love the manga.
What's amazing about Shippuden is that there's only been about 1 1/2 high budget episodes, while the rest have been terribly abysmal. I think it was 24 that was close to a sakuga episode. It's when Sakura fought the puppet guy. I think people said it was even Norio Matsumono.