No. The way it works is that if you press "bullet time" you and anyone that can see you, and anyone that can see them etc etc goes into bullet time.
Effectively you'll go into bullet time a) when you choose to and b) whenever anyone else on your screen is in it. The result is that there will never be a situation where one player is out of bullet time and they are shooting at someone who is in it, or vice versa.
Ok. Can someone explain this to me.
Scenario 1
There are 3 players in a server. A, B and C. Let's say that our game characters run at 1m/s. Let's say that bullet time slows down time by a factor of 1/2.
There are two corridors, X and Y, that run parallel to each other but are separated by a wall. The corridors are 5 metres long.
Players A and B are in corridor X and player C is in corridor Y. All three players start at the same end of the corridors (i.e. if you could see through the wall, they would be next to each other).
At the same time all 3 players start running in the same direction. Player C gets to the end of corridor Y in 5 seconds. But, players A and B go into bullet time together. Player C has reached the end of his corridor whilst A and B are only half way down corridor X.
One player has got to his destination twice as quickly as the other two, but the same amount of time has elapsed for all parties involved.
Scenario 2
3 players. A, B and C. Let's say the devs have modelled the bullets to travel at 100m/s. And remember that bullet time halves real time. It's worth noting that in interviews, the devs do actually say that due to bullet time every bullet is "modelled" as it's fired so the bullets do "exist" in the game world.
Players A and B are in a completely enclosed room but with no roof. Player C is on the outside of this room standing a few metres away from the wall.
A and B go into bullet time together. C, who is not in bullet time, fires a bullet over the room.
For C, the bullet will travel at 100m/s as he is operating in real time.
A and B are operating in bullet time therefore the bullet will be (relative to C) travelling at 50m/s.
All players are watching the same bullet, but this bullet is travelling at different speeds according to where they're standing.