NITRIX side effects.

I have been reading a lot about this new product Nitrix, which poeple are saying is supposed to "pump u up", and make you stay that way during the day. My goal is to get some more muscles, but mainly I want to get more definition. I'm thinking of getting this product, which should give me the extra push when I'm lifting, and also help me shed of the extra gelly. But my main concern, besides the headaches and nausea, with this product is the effect it has on your flexibility and how fast/big do you acctually get pumped up. I dont want to be walking around like a stiff robot with a bunch of strech marks. Also, does how does caffine effect you body, since NO is supposed to use up most of your water intake? Let me know if anyone can answer these questions, and maybe give me any other pointers. Thanks.