These three exercises hit just about every muscle group, and through them you can develop incredible power.
I personaly am not a fan of the squat. I've never been comfortable with that bar across my shoulders, it allways seems to press on that vertebra at the top of the back but the bottom of the neck, and as such i've allways hated it. There are of course alternate ways of doing everything, and i should have explored them when i was younger. It would have left me with a much more balanced body now.
Theres a reason you'll allways see somebody performing these exercises at the gym. They look impressive, and they work.