I have used and still use a couple of there supplements off and on. They are like any other supplement company... The products are to give you that little extra boost when your diet and training is on target. Overall, I think the quality is good, but the price is very high when compared to other supplement companies. Even online stores have high prices on their stuff compared to similar products from other quality supplement companies.
I'd say if you are into saving money look elsewhere, otherwise some of their stuff is effective in my opinion. I could never afford to use their protein as my primary protein supplement all the time. It tastes damn good, but there are others that tastes just as good and are cheaper.
Of all their products I'd say I like the Mag-10 the best. I had great success with even though others will say otherwise (everyone responds differently).