The manga is excellent, for the most part. In some areas it gets a little weird/weak, and not all the plot elements are "optimal", but for a super-long shounen it is remarkable.
Anime is a different story. It suffers from poor production, lackluster direction and horrible pacing. It is very, very overrated, and is due for a huge makeover.
For a long time, I've preferred the 4Kids dub to FUNimation's anime and the original Japanese simply because I don't think either of the latter two do justice to the manga, and it's not Oda's place to object.
That isn't to say 4Kids did a good job. I liked their intentions of making OP wackier and less "serious business" than Japan/FUNimation, but the end result left a lot to be desired.