The guillotine press – where you bring the bar down to your neck instead of the lower pecs – is a great chest developer. But there is risk. Keep these light and under control. This is not a bench press variation to go heavy on. And don't try to set a PR! This is bodybuilding, not powerlifting.
My favorite way to use it is 6 x 6 with 20 second rest periods between sets.
Nobody cares about injuries (boring!) until they get one. That's too bad, because sooner or later your knee, shoulder, hip, or back is going to start barking like a coonhound on the hunt. Even babes aren't immune.