I knew since college that Optimus Prime died. There's no way you can avoid not knowing that. Hell, that's why the Robot Chichen skit was so funny.
What I didn't know what every other robot died...horribly. Either Prowl or Ratchet actually has smoke coming out of his lifeless robotic mouth before finally expiring. Jazz died, and he was my brother's favorite. Ironhide managed to survive the first assault, only to get shot in the face because he grabbed Megatron's foot.
That I didn't expect.
Snakes Eyes is the ninja, right? Darn it, I kind of liked him...