In summary, Ghost Trick is a visual novel with a puzzle segment in each of the 18 chapters, but the puzzle is mostly cosmetic since the story is the main focus.
You play as Sissel, an amnesic ghost with a special power to manipulate small objects and go back in time 4 minutes before the dead of any recently deceased person besides himself. With that power he must find who is and why was killed, and he have time until dawn before disappears from this world.
Is hard to not compare it with the Ace Attorney games, not only because the developer of both series is Takumi Shuu, but also because like the AA games, the main charm of the game is the quite unique characters, each with distinctive quirks and behaviors, and see how interact with each other in a seemingly unconnected way, until you see the full picture in the last episode.
The story is pretty good, with several plots twist. Some of them are pretty evident (I figured Sissel identity at the end of the chapter six, and is one of the last revelations in the game) but some of them are totally unexpected (like the identity of the ghost that explains your powers at the beginning).
When a characters speaks, like most of the visual novels, a 2D image of the character is shown, but when appearing "on screen" they are modeled in 3D with astonishingly fluid animations. This aspect and the stylish character designs gives a really edgy feel to the game.
The puzzles consists most of the time to save a character from his/her death, manipulating the objects that you can possess. Even if you fail, you can go back in time 4 minutes and redo the situation, but the puzzles are fairly obvious, with only one way of solving them and usually you can do it with the first attempt. As usual with this kind of games, it rather short (about 10 hours) and have zero to none replayability value.
Since most of the fun is to know the truth at the same time as the main character, I won't spoil all the characters, only the ones you'll find early in the game.
The main character. He regains consciousness and find himself as a ghost, dead and without any memory of who is he or how was killed. Despite his looks, he's not as sarcastic as Phoenix Wright and usually is pretty naive.
The main heroine is this vivacious detective that have a more than passing resemblance to Gurren Lagann's Yoko. Seems to be the the only witness of Sissel murder, and is the first person that you need to help to literally escape from the death in hand of a hitman.