This is something new for me: protein shakes. Medically I can't offer advice about it (I'm weary about using foreign substances not recommended by a specialist), but the site certainly is has some positive signs:
- The badges at the bottom are clickable and they go to the respective sites which certify the site
- The domain is registered since 2006 and they are paypal verified since 2007
- They have an active Facebook and Twitter account
- They use paypal / google checkout for payment which reduces your risk considerably
They also have also some less positive signs:
- There is no physical contact address
- The registration details are hidden by proxy registration
- The phone-number is a generic one (I would have liked one which coincides with the physical location)
All in all I would recommend this site for small purchases from inside the USA (they don't deliver internationally). Also, I would consult a doctor (or multiple doctors) about the possible effect of the substances. In my view (and I'm no doctor) this is more serious than the homeopathic or "natural" substances and it should be handled with care. Then again, I'm also against medicine / medical devices (like glasses) being sold in places without expert supervision (like supermarkets).
Full disclosure: this is a paid review from ReviewMe. Under the terms of the understanding I was not obligated to skew my viewpoint in any way (ie. only post positive facts).