I was surprised how well this was priced. It came in a big tub filled to the rim I decided to play it safe and went with Double Chocolate. You do need a shaker with a huge circumference or just use a blender, because the scooper is so big, the powder just goes everywhere if you try to pour it into a shaker. Alas I finally figure out I could use a funnel if necessary (in case my bigger shaker bottles were dirty mcnasty).  
   
I first tried it with 16oz of fat-free milk as recommended, and it mixed up good. No clumps, which surprised me for how much powder there was. The taste was damn good! For only having a couple grams of sugar, it tasted like a glass of chocolate milk where you added a ton of Hershey's syrup. Probably has something to do with the 85g of carbs (You need carbs, not just protein for muscle gains) It was very satisfying and after I drank it, it made me really thirsty for water-don't know why, but I felt the need to down some water which made me feel even more full.  
   
With water it's as expected not as good as milk, but still pretty satisfying.  
   
It calls itself the 'High-Protein Lean Gainer' and it is just that. I just took 1 serving a day, usually sometime after breakfast but before late-afternoon. You can't expect to go through 1 tub of this and expect to gain some solid weight. It's a marathon, not a sprint. At maximum I think you could gain a clean 5lbs with 1 order of Pro-Complex Gainer. I think I gained between 3 or 4 pounds, but I noticeably had some more lean muscle, specifically in my shoulders and arms. I don't care how slowly I gain weight, as long as it doesn't add fat. I kept all my definition especially throughout my abs and core. Still looked ripped and cut, so I'm very glad this didn't add fat.  
   
Optimum also has another gainer, Serious Mass, which has much more calories per serving. You'll be putting on weight a lot faster, but you will probably sacrifice for a little fat gain.  
   
I'm also wondering how this would fair on a CKD diet-NOT during it, but on the 'carb up' days. I think this would be no less than optimal to give your body when it's starving for carbohydrates.  
   
Bottom line you're looking to add muscle quicker than just standard protein shakes and a good, clean diet, this is your go-to-gainer. Depending on how many servings you take a day (I only took 1), you will gain weight slowly, but still lean muscle.

Such a good gainer. ON pro complex gainer is cheap and of very good quality. The Chocolate is the one I get most. It mixes easily in water.. And goes down smooth. It's a refreshing blend of carbs and protein without too many fillers. I work out a ton and I needed a good gainer, so a friend of mine recommended pro complex. I haven't looked back. For the taste and superior quality you can't go wrong.

Big Maks here for another supplement review. This is honestly the supplement that has helped me turn from a skinny 160lb college freshman to the lean 190lbs. If you have had problems putting on muscle and already try to eat as much good food as you can but still cant put on much weight this is the must have supplement for you!!!  
 
Pros- Great Taste, Mixes really good, and really solid formula/ingredients  
 
Cons- I cant think of one, maybe not enough servings even though you not going to take the full suggested servings because thats just too much in your stomach.  
 
Conclusion- If you take even half scoop servings twice a day your going to get 85g of good carbs and 60-75g(depending if you use milk or not) of muscle building protein with 650-800 calories. Thats precisely the boost in addition to a solid 5-6 meal a day diet that a hardgainer needs to put on that weight, tired of being skinny? then its time to get Optimum Nutrition Pro Complex Gainer and start growing!!!!