I dont agree with the use of RMP to develop "rankings" like this, but those that did the study defend it:

http://collegeaffordability.blogspot.com/2009/08/in-defense-of-ratemyprofessorcom.html
http://collegeaffordability.blogspot.com/2010/08/in-defense-of-rmp-part-two.html

http://www.grandforksherald.com/event/article/id/186487/group/Opinion/

If some students put as much effort into doing classwork as they do into trying to avoid it, we'd have a greatly more educated world.  I may get a lot of crap for this stance, but the way to get better at anything is to challenge yourself, not take the easiest way out you can find.  Using statistics from sites like this to pick which school to attend is a step in a bad direction. 

My suggestion?  Find a school that has the program you offer, doesn't have a graduate degree in that area, and has small classes, and then worry about everything else.  I'd also suggest looking for a place that has good food.