Wow. This is definitely the best game I have for the 3DS. Both the gameplay and graphics are awesome.
The game features a bunch of modes. "Chronicle" is the storymode, where you battle through 5 chapters summing up what happened in DoA 1-4. It's a mess, but it's still really fun. Then there's Arcade, Survival and Tag Challange, 3 other fun modes.
There's also online play, but it's a but of a mess. You can battle random strangers (from the entire world or just your region) or your friends. But the framerate can sometimes slow down a bit, regardless of who you're playing with.
There is a total of 25 characters to play, and maybe there's one more secret character? I won't spoil that. But there really is a lot, and they all have at least 3 costumes each. Every day you get a new costume for a character through SpotPass, so a character can have up to as many as 7 costumes!
Costumes aren't the only "prizes" you get, though. Sometimes you unlock a figurine of a character, which you can then look at in 3D, and take pictures if you want. But wait. You haven't heard the number of figurines. It will blow your mind... Because there's a whopping 999 figurines to collect! After about 10 hours I had only colected 12% of the figurines!
The game is really beautiful, with or without 3D. While 3D adds a really cool depth to the game, and stuff (the logo and other titles like "Winner" or "Loser") literally comes out of the screen, the framerate does suffer from this. It's halved to 30 fps, while the 2D mode runs at a unbelievably smooth 60 fps.
But overall this is a really great game. I spent a couple of hours on the Chronicle mode, and a bunch of hours on the other modes. It's really fun! So it's definitely a must-buy!