I've never been the hugest fan of adventure games. The last ones I really enjoyed were Maniac Mansion and Dark Earth. I suppose Indigo Prophecy qualifies as an adventue game too.
Anyway, Phoenix Wright. Great game. You play the role of Phoenix Wright, a fledgeling attourney. I'm not sure what kind of screwy world Phoenix lives in, but things are quite a bit different in his society than in ours. If you can get over the fact that the laws in this game bear little to no resemblance to those in real life, you should really enjoy it.
In each of the game's five trial cases, you'll first meet and interview the client, and then investigate the crime scene and interview witnesses, gathering evidence and learning more about the case. It's a bit odd that you play the role of both the detective and the lawyer, but it makes for some interesting gameplay.
After you've gathered sufficient evidence, and asked all the right questions of the people you need to talk to, (the game won't let you advance without everything you need) it's time to go to trial. Your job in the courtroom is to get a verdict of "NOT GUILTY" for your client. This is done primarily by cross-examining witnesses, and finding contradictions in their testimony. This is done either by pressing them on certain issues, or by presenting evidence which points out a contradiction in one of their statements. If you attempt to present evidence which has no relevance, the judge penalizes you. If you're penalized too often, the judge declares that he sees no need to extend the trial, and immediately declares your client GUILTY. It becomes a bit much when certain witnesses go to such lengths to cover up the truth in their testimony and the judge just puts up with it, but thankfully Phoenix Wright is up to the challenge.
After each day in court, you hit the streets again, now armed with new knowledge which you've learned in the courtroom, and continue to question people and gather new evidence. in the strange world of Phoenix Wright, all trials must be completed in three days - apparently trials were dragging on so long that this odd legislation became viable. So you can expect your cases to last no longer than three days, which breaks each case up neatly into up to six sections: three investigation chapters, and three courtroom chapters.
The majority of the game is text, but the storyline is good enough that it never felt boring. And the character animations are always interesting. Between the colorful text and the outlandish faces the characters make, many of the characters in Phoenix Wright develop more of a personality than other video game characters who have full voice acting. Quite a bit of the game is entertaining for its understated humor and over-the-top characters. When a critical piece of evidence is revealed, it's great to watch the witness's eyes literally pop out of his head and his hair to frizz out as if he'd just stuck his fingers in a socket. It's very cartoony, but that's a large part of its appeal.
One review I read somewhere (can't remember where) pointed out that this game feels more like a fighting game than a murder mystery adventure game at times, largely due to the visuals and the music. When Phoenix gets on a roll in the courtroom, you'll see him on a background of blurred moving lines amidst music that sound like something out of Street Fighter, and suddenly you feel like you're in an episode of Dragonball Z.
The game has a number of very interesting puzzles that utilize the DS's unique control scheme in interesting new ways. These puzzles become much more evident later in the game, especially in the final case. For example, you use the stylus to examine specific parts of a crime scene, and you can shout "Take That!" into the microphone to present evidence, or yell "Hold It!" to object and press a witness on a certain point. Later on in the game, there are some really great puzzles that involve assembling broken pieces of a vase, using the stylus to spray luminol, or even using the stylus to drop fingerprinting powder and then blowing into the microphone to blow excess dust away.
Due to the game's linear nature, there's very little replayability, but I had a lot of fun with this game. It's easy and lasts a fairly long time. I'd recommend it to anyone with a DS.