This second installment of the Naruto animated series picks ups two years after the event that have transpired in the original series excluding the filler episodes and story arcs where. The actual end of the Naruto story was when Sasuke Uchiha the rival and best friend of the protagonist named Naruto Uzumaki has left the Hidden Leaf Village to become a "missing-nin" or a renegade ninja to learn under the villainous Orochimaru to be powerful enough to take on his brother another missing-nin and S-Class criminal Itachi Uchiha, who had murdered the entire Uchiha clan. Sasuke was the only one spared. To understand Naruto Shippuden, one must be familiar with the earlier Naruto series from when they were twelve to thirteen years of age.
Like in the manga, Naruto: Shippuuden goes more in-depth with the sinister dark organization known as Akatsuki which Itachi is apart of. Akatsuki had barely made an appearance in the earlier anime episodes and manga chapters but have made a presence which Sasuke started to doubt his own abilities. Watching the first few episodes, I have seen that the anime has done a good job presenting the transition over two and a half years as the characters have gone through several changes which looks to be a very important part of their growth throughout the story let alone the series.
Naruto Uzumaki himself is no longer the typical prankster and showoff but seems to be a bit more mature. But he tended to pick up his teacher Jiraiya's perverted ways.