They are also extremely hard to do correctly, and any mistake in form can and will injure you, either over time or due to one bad lift. I personally can't understand why they are so often recommended to beginner lifters.
Buying a book like Starting Strength by Rippetoe and starting with low weights goes a long way to getting your form good enough that you won't seriously injure yourself.
Just to add one anecdotal data point, I've done that and so far(for about 1 year) I have not had any problems. I do squat, deadlift, bench press, press, pullups, and situps. I've worked my way up to 230lbs + bar in deadlift and 200lbs + bar in squat. I experience a little muscle soreness in the back but that is all. I still need to watch what I eat and walk to burn calories since I still need to lose a little weight.
