From
IGN:
The design is a point-and-click style adventure that puts players in the role of Phoenix Wright, an up-and-coming attorney that's a little green around the gills in his trial experience.
In fact, the first chapter in the game is Phoenix's premiere trial, which makes it a perfect opportunity to train gamers in the process of cross-examining witness testimonyÂ…pretty much the meat of each of the several chapters in the Phoenix Wright: Ace Attorney design.
But it's not just about the trial process, and in most chapters there's a heavy focus on digging for evidence in order to prove a client innocent. The Nintendo DS system's dual-screen design makes it easy to navigate all the menus for dialogue and investigation; the game isn't much more than a text adventure with a graphical user interface, but navigation is much more intuitive pointing and clicking on a touch-screen than tapping around a cursor using the D-Pad. But you can play that way too if you want.