Yes, indeed. Unless you need to train for a sport-specific purpose.
Seriously, if you do them s-l-o-w and go all the way down, you activate all your major leg muscles as well as your smaller stabilizers. If you get bored with squats, you can do standing lunges. I do 50 s-l-o-w squats then as many s-l-o-w lunges as I can do (30 right now...) Be sure to follow Mark's progression to get maximum results. I'm getting ready to move up to level 5.