He could have watched the classic weakness of the f-pawn better. Bf3 move clearly shows he missed the mate threat! Good job not missing that.
I think there is some room for improvement starting with 3... Bb4? White could have replied 4.c3 to gain tempo and support the classic central advance d4. Other than that it looks well played by you.
Sometimes you just can't foresee an attack. I think this was one of those situations for white in a game I recently played. After seven or so solid developing moves, my opponent set up a fried liver attack, so I formulated a plan to make the best of the situation, and it turned into a victory for me by the eleventh move. This is an example of oen of those mates you just don't see coming. Even I didn't see it until I was two moves away.