If you've been following the game since it was announced for Japan (As Gyakuten Kenji) you should already know what Ace Attorney Investigations: Miles Edgeworth is like - It focuses far more on the investigation aspect of the previous Ace Attorney games, leaving out the court scenes entirely.
The big new feature is the "Logic" system. With this, Edgeworth can make links between pieces of evidence to come to logical new conclusions, which can then be used for further investigation. Once you think you know the killer, you can confront him/her and try to find contradictions in his/her claims, much like the cross-examinations in the previous games.
While Phoenix Wright apparently doesn't appear in the game at all, you can expect other old characters - Dick Gumshoe, the bumbling detective, is your partner through the whole game, and you'll also get help from Franziska von Karma and new character Kay Faraday.
To go with the announcement Capcom has of course also released a trailer and some screenshots. The trailer can be found below, while you can view the screenshots below that: