Some random thoughts:
1. A non specialist reviewer is a good idea. One of my sites had a feature that every IT professional who looked said was fine but which a significant proportion of customers had a problem with. (The fix was trivial)
2. Bounce rate - how are people arriving? Is the information that they want on the landing page? If not is there sufficient information to make them want more? Is navigation obvious and easy? From my site stats I think a significant proportion of web users have an aversion to clicking internal links within sites that they visit.