I've been taking the Ultimate Mass Pump Stack for just a few days, and I can already say it rocks.
If you guys aren't keen to this already, its a stack of CM, CEE, and AEE bulk powder that Nutra is selling for a STEAL!
I've used various forms of Creatine, I've always liked Citrulline Malate, and I've never tried Arginine Ethyl Ester.
The closest thing I have tried to this is MRM Metabolic Pump, which is Creatine, Citrulline, and Di-Arginine Malate, and I really liked that product---but it was expensive.
The main thing some might not like is the taste...its very hard to take real dosages of this without requiring a ton of liquid to dilute the flavor. It doesn't bother me--I can go 2 grams of each in 8 ounces of OJ, but it might bother some.
I don't take it for the taste though--Improved endurance and massive pumps...I like this!