To put it bluntly, you just bought a drum of gatorade with a little bit of protein added for lot of money. Take it immediately following your workout and when it runs out never buy it again. Instead, spend less money on whey protein and get your carbs from something cheaper and more filling (like oatmeal). There are no side effects to what you are taking and my advice is to stay away from GNC. They are overpriced and sketchy sales people who don't know their shit.
By the way, taking this product is for gaining mass not toning. Read the label and you will notice how many calories, carbs, and sugars it has.
After you are supplementing whey and want to add even more endurance, I reccomend looking into a creatine product, ex. Micronized Creatine from a reputable company or SwoleV.2 if you are a creatine non-responder (its a creatine coctail).
one of the many reputable micronized creatines info:
http://www.bodybuilding.com/store/as...ocreatine.html
SwoleV.2 info:
http://www.bodybuilding.com/store/syn/swolev2.html