In my personal experience, I liked it. AMP (Amplified Wheybolic Extreme 60) helped me a lot with my recovery after hard intense workouts. But I didn't see a significant change on muscle mass, probably because I just tried a bottle of AMP Amplified Wheybolic Extreme for 2 weeks. (Most protein powders recommend to take the product for 3 months for best results).
GNC's AMP is a little expensive. At $61.99 a 3lbs bottle or 17 servings (3 scoops) of 60 grams of protein.
Directions: Take 1 serving (3 scoops) of GNC Advance Muscle Performance (AMP) Amplified Wheybolic Extreme 60 with 12 oz of water, 30 minutes after your workout. On non-training days take a serving of AMP first thing on the morning.
In conclusion I liked GNC AMP, but it is costly. I will have to save money for my next bottle or find a similar, less expensive protein powder.