The MERE EXISTENCE of this game. The mere existence, my friends.
How about the fact that it's coming to North America and Europe?
In the trailer, we get "There is a huge contradiction in your argument," from Wright and then "Mr Wright... I think we may have been making a horrible mistake," from Layton. Holy crud, am I actually watching fiction's two most over-the-top truth-revealers calling each other out?
TGS trailer: Layton and Phoenix both pointing dramatically at the screen, together. It is awesomeness to the highest degree.
The ability to Object to puzzles. Just the idea of calling someone out for giving you a purposefully unsolvable puzzle and refusing to play by their rules sounds really empowering, especially if you have experience with being frustrated with a riddle because the person who gave said riddle mangled the instructions. Unfortunately, it was only used once in the game itself.
Layton having his own Objection! Hold It! and Take That! sound effects, even having his own Objection music theme.
Not just that, but during the last trial, there's a segment where you switch control from Phoenix to Layton, marking the first time in an Ace Attorney game where the player controls the prosecutor during a trial instead of the defense.
Phoenix having new "Welcome!" and "Hang on!" sound effects.
The Game Itself
Opening of the game itself, a transforming black golden clawed one-eyed THING bursts into Layton's office and kidnaps his client using telekinesis and generally blowing things up. Layton is surprised for one millisecond, and then takes it on. As it bursts through the window and most of the surrounding wall screaming into the night with its captive; he frets that this is "troublesome", especially since he promised he would protect said client.
Phoenix for going toe to toe with Inquisitor Barnham in court, something no one ever did in the history of Labyrinthia.
In the second trial (first in Labyrinthia), Phoenix is on the ropes, when he gains an ally who makes a positively awesome entrance:
Prof. Layton: HOLD IT. (Enter Layton, head tilted forward so the brim of his top hat obscures his eyes)
Layton goes Big Damn Heroes with his own "Objection!" during the first trial to help Phoenix with the Grand Grimoire, after he realizes that his usual tricks (forensics, photography and even logic) aren't working. Since magic is a big part of this world, he needs to know about magic too.
Layton's "Objection!" theme being a huge contrast to Phoenix's is pretty neat; Phoenix's is loud, staccato, and excitable, with a fuller sound due to having more instruments behind it. Layton's is calm, collected, smooth, slow, restrained, and most of all, classy, played largely by only two instruments, particularly the violin. And yet, it carries the same dramatic and triumphant weight of Phoenix's theme.
At the end of Chapter 4, Maya gets one when she refuses to let Espella sacrifice herself and saves her from the Flame Cage. Unfortunately, in the process, she gets trapped is sent into the flames herself.
Phoenix gets another one when he confronts Barnham after Maya's apparent death. Even in his home series, we've never seen Phoenix this angry before. It clearly leaves an impression on Barnham, as he lets them escape shortly after.
Judge: (to Phoenix and Layton): I have NEVER seen anything like this! You change hearts and minds and reveal truth through words! What is this?" Layton: It is called "Logic."
This is the very first time that Labyrinthia has ever been exposed to logic, but Inquisitor Barnham shows that he's a fast learner, and begins firing back with logical arguments of his own almost immediately.
Barnham gets one while outside Labyrinthia, in the Eldwitch Woods. The Great Witch has disappeared and the Shades, her servants, are panicking. Upon discovering Barnham, who has been investigating, they immediately attack him. Barnham fights off the five of them with a few effortless sword strokes. He's the "Sword of Labyrinthia" for a reason.
Layton again, going Big Damn Heroes on Maya after it was revealed that she was alive and well. With a stick.