I don't like the arc in general, but Eneru is easily one of the best One Piece villains and when he finally meets Luffy is one of my favorite scenes in the show. Granted, a lot of the other shit really builds up to that moment, especially since he really might be the most god-like character introduced in the series so far.
Granted, one of the things I hated most about the arc was the Mantra ability, which later on becomes a bit of a staple in the series, even if the usage doesn't seem as OP as Eneru's and his cronies'. That form of Haki lets most characters sense things happening close to them, whereas the monks could sense things from great distance.
That was just a retcon to make it the same thing as Haki. ---