More details on Titanfall are slowly revealing, the latest is the confirmation on how many titans are in the game. Community Manager Abbie Heppe has mentioned on her twitter about only having three titans available. The three Titans  each have their own unique traits, it should give enough variety in the battlefield.
Also Respawn has confirmed the Beta will not be under NDA like the alpha released a week ago. You can catch Titanfall Beta on Valentines Day for the Xbox One and PC and in stores March 11 according to EA release schedule