It's proper title is Official Casebook Vol. 1: The Phoenix Wright Files.
First of all, I don't recommend reading it if you're not a fan of the game. The jokes and references will go way over your head, and a lot of it will be meaningless. It might still be a good read regardless, but it's meant to be a companion to the video game series. What this book is, is a compilation of short stories and 4-panel gag strips that are drawn and written by various artists. Basically, each story has a different artist. Some are better than others, but they each have their own charm. The book was released here by Del Rey manga, for $14.95. It's actually two books; I'm not sure where the split would be, but it was published as two separate volumes in Japan, and one here. The second US volume will be an Edgeworth volume, so it seems Del Rey will publish them as character collections, which is good. I don't recognize any of the artists' names myself (and some of them are probably pen names anyway, and many are likely doujin artists), but I'll see if I can't find some links to go along with it.
Fans will be delighted to discover that a broad range of the characters are presented in the book, though many only make brief cameos (or just appear somewhere in the background). Phoenix, Maya, Pearl, Mia, Larry, Edgeworth, and Gumshoe all make plenty of appearances, along with the Judge, Oldbag, Godot, Ms. Von Karma, Mr. Grossberg and even Mr. Armstrong.
Progress Toward Tomorrow, by Tamako Yamauchi
Turnabout Inference, by Kei Nisemura
Turnabout Illusions, by Seventh Gear
A Small Case in a Small Office, by Wataru Yamasaki
Kind Lies, by Tsubaki Mikage (seems to be a doujin artist, mostly BL I think)
Turnabout Misunderstanding, by Kaname Uchimura
Motive Power, by Naruzou (doujin artist, likely)
Turnabout Day Off, by Yuya Kurogami
Turnabout Kitten, by Natsu Otono (possibly)
Spirit Medium or Bust!, by Kaoru Osada
It's Not Easy Being a Defense Lawyer, by DAIGO
A Turnabout Day Together, by Masao Aona
Turnabout? Food Fight, by Yorozu
Car Life, My Life, by Tamako Yamauchi
Ball Search Team, Head Out!, by Tomo
The Legendary Defense Attorney, by Kikuchiyo Anko (likely doujin artist)
Maya's Blue Skies, by Wataru Yamasaki
The Mystery of the Missing Manju, by Tsukapon
Encounter with the Unknown, by Rin Hashiba (maybe)
Turnabout Big Turnaround, by Shinosuke
Four-Panel Comic Strips, by Kikuchiyo Anko, Aira Kanou, Kiyono Shimanda
I enjoyed all of them for the most part. The art styles vary pretty drastically, and the only one I really had any sort of problem with was Kei Nisemura's piece, because the characters all looked like they were constipated through the whole story. There were a couple of bizarre stories, and the language/writing/translation was really off on one or two of them. The characters are captured exceptionally well though, and the stories are a lot of fun (though there are one or two that are a little on the serious side). The stories range from ghostly clients and lost kittens to quests for food and missing toy balls. If you like the games, and if you're like me and are always left wanting more stories when they're over, then it's worth picking up.