It is more difficult because a lot of mechanisms are based on your position. When you are 2, it is more difficult to know when the bullet will target your character, and if you don't move as a same person you have a risk to be hit by old position of the second character.
The hardest part is the Run'n'gun, as every event is triggered by your move, so if the second player is behind you he'll get the delayed event, so less natural from his position. I'm not sure I'm making sense haha, you need to test by yourself!
I think the revive is a plus though