Some Japanese readers: Skypiea was slow and I lost interest in the series and I stopped reading.
Comprehensible. The japs have too many gods which surely are opposite to each other in some cases.
Certainly, Skypiea was slow in the Noland's flashback and all the protagonists facing the Death Game. But the feeling for so many catholicism countries to defy God in a completely new landscape depicting Heaven to end with the protagonist with the power of the devil holding himself the title of the King of the Seas before the showdown. Epic in the most raw way to take it.
Skypiea is my favorite arc, it holds many ingredients to be added in any outcome possible for a place in the series. The religion involved also delivers a great taste, usually it's needed courage to write about it, despite any resemblance to start comparing and pissing people.