Well in my opinion he changed a bit, in part one he was cold headed and had a clear goal, plus he was really skillful and resourceful, he was a prodigy and didn't need anybodys help to beat his opponents
In part 2 he became emotionally unstable and he didn't have a clear goal, he just traveled around the world changing his goal every two chapters, thats why i prefer part 1 Sasuke
He did have a clear goals for most of Part 2.
Sasuke changed goals after hearing life changing information.
Goal 1) To Kill Itachi
Change 1)After hearing the truth about Itachi,and the Uchiha massacre.
Goal 2) From that his goal changed to destroying Konoha.
Change 2)After speaking to Itachi,seeing how he had no remorse,or anger towards Konoha.Sasuke questioned if he should destroy Konoha or not.After speaking with the Kages,and learning the history of Hashirama's life,Madara's life,the history of the Uchiha,Senju, the Shinobi world, what the purpose of Shinobi are, Villages, how they're important,etc.
He decided to protect Konoha,become Hokage,and do his Revolution,which was his 3rd Goal
Change 3)After fighting Naruto to the point where he couldn't move.He opened up to Naruto,the guy who was willing to risk his life to help him.And he decided to work with him,rather than do things alone.
Since then his goal has always been too protect Konoha.He travelled the world in order to better understand it.To see how the world is,and find ways to ensure peace is maintained.
Masashi spoke some about what Sasuke did on his journey in an interview a few months ago.
4th paragraph
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And judging from the spoilers,he's also been dealing with the new Akatsuki,and travelling around to get the Sharingan they stole from Obito's hideout.
No one stays in the same mindset 24/7,and as people grow up,there goals tend to change.Especially after life changing events.
Sasuke's changes were good.