Could this dethrone Jump Superstars reign as best DS fighter? From what I've played so far of this game, it certainly stands as a contender. This game is everything the GameCube game wanted to be, but so so much more.
First off, the game has a legacy of greatness before it. It is developed by none other than Treasure, who were responsible for classics like Gunstar Heroes and Guardian Heroes. The character animations in this game is near flawless. Everyone moves and fights as they do in the anime it spawned from. One thing it has in spades over Jump Superstars (or most DS games for that matter), is the fantastic voice work. Every super move, every attack, every groan and battle damage sound is done by the seiyuu for each respective character from the anime.
The range of characters selected for this game is quite interesting. There is the old standbys: Ichigo, Renji, Orihime, Ishida, Chad, Byakuya, and various other captains and vice captains, but some of the secret unlockable characters really stand out. Not always in the good way either. The two joke characters in this game (Bonnie, Ganju's boar and Kon) waste space where other characters that were left behind (cough Urahara cough) could have been in. Other than that, the selection of hidden characters is great. Yachiru is ready for action for the first time in a Bleach fighter, as is Tatsuki and various other spoilerific characters.
The only real downside to this game really effects only the folks who don't read Japanese. Ichigo's story mode is very very muddled and confusing unless you have a translation guide or know some japanese. There are special conditions for fights that are not so aparent for those who cannot read Japanese. Thats not too huge a deal however, as mulitple translations and guides exist on the 'net.
With that said and done, I'd really like to mention something that the DS version of the Bleach game has done 100% better than the Gamecube version: Ban Kai supers. Rather than some crappy still screen animation as shown as the cinematics in the Gamecube version, you actually get to use these characters's ban kai moves. You can control Ichigo's Tensa Zangetsu. You can use all 3 forms of Byakuya's Senbon Zakura Kageyoshi. You can even use Tousen's ban kai to temporarily turn your opponents screen black, giving you the upper edge.
Final verdict: Skip the gamecube version all together. Bleach DS: Souten ni Kakeru Unmei is a winner!