And from which episode story heats up?
For starters, Arlong Park arc (episode 31 to around 46, I think).
Alabasta saga stuff is pretty average, with some of the decent arcs in the middle (Drum Island etc.). Skypiea has a lot of funny moments, but it gets dragged out a lot.
The next batch of really good stuff comes with Water 7 saga... The whole plot is just awesome.
Following that, Thriller Bark is again full of funny gags but pacing wise it kind of sucks.
After that, all the stuff from Sabaody to Marineford is definitely some of Oda's best works.
Fishman Island felt like a setup arc for the New World, average stuff. Punk Hazard was a setup for Dressrosa...
And Dressrosa speaks for itself. It's definitely one of my top 3 arcs.