I know I'm double-posting here, but just to add on to what makes Titanfall so awesome
A big part of the game's fun-factor is the emergent experiences; chains of events that you don't really instigate deliberately, but rather, they just happen and it's really cool when they do.
A recent example I can think of is a few days ago, I was running along the upper corridors of Rise, there was an enemy titan on the ground below me with a human pilot inside of it. I jumped on top of it, ripped the armor off and started throwing satchel charges inside his Titan to sabotage it. The enemy pilot didn't have any electric smoke to deter me, so he ejected from the cockpit and jetpacked upward so he could get get me in his sights. When I saw him eject, I jetted up as well, simultaneously mashing the button on my detonator and dealing a big chunk of damage to his Titan. We both landed on a bridge above his Titan (him before me) and I managed to kick him to death square in the face right as we landed. Then I turned around, pulled out my rocket launcher and dealt a final blow to his Titan to doom it. His Titan turned nuclear, and when it exploded the blast radius took out two other pilots as well. I was like, "YES!".
That's the kind of story I can't really muster from any other FPS.
Another example I can think of (happened a long time ago closer to release, can't remember which map), I was inside my Titan being rodeo'd by an enemy pilot. He managed to doom my Titan, and somehow in the commotion of things, I actually fell off the map into a pit at the very last minute. I pressed the eject button, shot up from my chair and managed to fly back up and barely climb my way back onto the map, whereas the enemy who was sabotaging me basically fell to his death along with my derelict Titan. Made me laugh my ass off.