It is like any other FPS, but with Titans, you kill enemies, and then kill more enemies, and then kill more enemies. It is an extremely fun game at first though.
I'd enjoy Titanfall more, if there weren't only 6 game modes:
Attrition (Kicked Up Team Deathmatch),
Last Titan Standing,
Capture the Flag,
Pilot Hunter (Team Deathmatch),
Domination, and the
Online Campaign (No Singleplayer).
More unlocks and game modes would continue to reel in people, but like most FPS's it gets repetitive.