Oda is an excellent writer and most of his chapters end up covering several bases so it feel like you've actually read something after you get done.

I believe it's due to this that some chapters just translate so well to anime form.

Episode 397 essentially cover chapter 503 along with a few added scenes. Despite covering only one chapter, i thought that episode was really good and didn't feel that stretched out. Sure One Piece have a slightly longer intro scene along with a recap to fill some time but that was still roughly 17 minutes of content that was covered by one chapter. Try doing that with something like Bleach and you'll end up with a 10 minutes staring contest.

Certain things like the music during Rayleigh appearance add impacts that was missing from the manga. I think the anime is doing a fine job with the adaptation, and the upcoming content will just looks amazing animated. I suggest at least waiting until this arc is over before starting to read the manga.