I finally revised the story in 7/2014 (after it was completed in 4/2009), so if you read it before then, I humbly ask you to reread it, in preparation for the sequel.
However, it's not necessary. The basic plot outline is the same. The missions went about the same, and the main point — Naruto and Gaara becoming friends, Gaara no longer trying to kill everyone — remain the same.
Kushina purposefully brought Naruto to Hidden Sand and made a deal with Kazekage to let Naruto become a citizen, in exchange for improving Gaara's seal. (Gaara can actually sleep since then, but rarely does so.)
Naruto volunteered to be on Gaara's team, rather than being assigned, and Kankuro was added only on the Land of Birds mission.
The book Naruto gives Gaara is Tale of the Gutsy Ninja, rather than his mother's journal.
Temari tutored Naruto before he became a genin. (Like Gaara does with Matsuri in the last filler of Part I.)
I also changed whether English or Japanese names are used for some things, but everyone in the fandom is used to that sort of thing, I guess.
So yeah, I finally started the sequel. Haha.