Here's the 411 from a follower of the anime and an avid gamer.
* This game looks gorgeous. The cutscenes are just jaw-dropping - looking just like the anime. In-game graphics also look beautiful, capturing the scenery from the series.
* The voices are spot on to the original series. The choice is available for Japanese (with subtitles) or English. The sound effects are spot on both during cutscenes and mid battle.
* During story mode, I felt like I was playing the anime. Combat, though it seems very shallow, is done very well. It gets deep and challenging to master in multiplayer mode. Certain characters are clearly more powerful than others, but choosing a team carefully and combining their strengths can help you out skill your opponent.
* Quicktime events are seamless and do not take away from the exciting boss battles
* Certain plot elements were done quite well (see below for details)
Con's
* The plot, though done well, has been modified quite a bit from the original series. While a scene involving Naruto and Sasuke's first reunion added an amazing side plot and battle sequence, other major plot components like the Hidan and Kakuzu arc were cut short and replaced with a few lines that would confuse anyone who didn't follow the anime/manga.
* The "side quests" in the main story mode are simply mindless and gathering is a bore.
* Becoming skilled in multiplayer will take a lot of trial and error against certain characters who are over powered, but once achieved is very rewarding.
TL;DR: Visually fantastic, some plot additions add to the series if you follow closely, others take away from it. Gameplay makes you feel like you are playing the anime. Sound/music is beautiful. Side quests are boring. Multiplayer is difficult against powerful characters, but rewarding when mastered.