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.
A competitive powerlifter recently contacted me to correct his woefully pathetic bench press. After a few tests and some obvious visual clues, I realized that his triceps were holding him back from pressing up big numbers.