The "Safe" ending was made of this. For starters, after you discover Ace's identity, you call everyone up and expose Ace as the killer, in a manner similar to Ace Attorney.
And afterwards, Snake proves he wasn't just bluffing about his strength. Ace is either apparently the strongest, or second strongest (after Seven) character in the game, and is armed with a gun with six bullets. Snake is a scrawny, pale guy with a false left arm (that has had its hand crushed). Yeah, and he's blind. Snake takes each of the bullets and lunges up to Ace.
The Memories of the Escape feature. The ability to replay each of the 16 rooms all over again, without having to restart the game.
The True Ending is just filled with them. Who knew that the act of turning the DS upside-down would be one as well?
The final puzzle alone is a wrap up of Moment of Awesome, Awesome Music and Heartwarming Moments all in one.
Junpei: "I'm gonna do this on my own, [with my own mind]! I'm gonna solve this problem!"
Also from the True Ending, after Ace fails to open the q door, Seven knocks him to the ground with a single punch. It's very cathartic to watch.
While we're talking about Seven, how about him saving the kids in the previous Nonary Game nine years ago? A sublime example of Big Damn Heroes.
Let us not forget that the entire plot revolves around the fact that rather than just dying when put into a death trap that she lacked the skills to overcome at the time, Akane Kurashiki engineered a Stable Time Loop in which she'd create the means for her continued survival nine years after it happened.