Aside from the English voices a great multiplayer game.
The Good:
Remember the days of Street Fighter when you'd play a friend who you could never beat but had fun trying none the less? This game is for you then. Having a tournament or just playing "winner goes on" is probably about the most fulfilling experience while playing Naruto: Ultimate Ninja.
The graphics seem very manga-like, something you'd hope for when playing a game that came from the manga and then eventually the TV show.
If you enjoy the English translation of Naruto featured on YTV or Cartoon Network you'll be pleased to know that the same voices are used for the characters in-game.
The Bad:
If you hated the English-dub but loved the Japanese-subbed version of Naruto, you'll probably just skip through a lot of the dialogue because the voices for one don't fit the character and two, they're just damn annoying.
Like most fighting games, the story-mode in this game lacks depth and lets face it... a storyline. Kind of dissapointing that the developers didn't put more effort into this when translating it for the English audience.
You only start off with 6 characters (Naruto, Sasuke, Sakura, Lee, Kakashi-sensei and Shikamaru) which is dissapointing especially if you're used to the 24+ player lineup from the Japanese game(s). The good thing though is that each player does actually have a different play-style instead of different animations for the same move. (For example, Hatake Kakashi is a lot faster and his movement is more fluid than Neji who uses a lot of counters and is generally average until he uses his Byakugan and his attacks temporarily become much more powerful and for the most part, unblockable).
So if you can get through the high-pitched, badly-chosen voice acting, a slapped-together story-mode and if you have at least one friend who enjoys these types of games like you, then it's worth the buy. If not, just rent whenever you're headed to a LAN party, etc.