low rates mean the control surfaces move a certain (SMALL) amount for just lazy sport flying. High rates the surfaces move ALOT further therefore the plane is MUCH more rsponsive to VERY SLIGHT control stick movements. You can adjust these with a standard radio by using the closest holes in the servo arm and the furthers out holes in the control arm on the control surfaces. Does this make sense? Low rates will make the plane less sensitive to control inputs on the sticks. This is great for maidens and for planes that were intended to do aerobatics and 3D if you just want to loaf around and not 3D.
EDIT: We beginners are better off on low rates for ALL planes until we learn to handle them From what I've heard this is a very stable plane BUT as stated before it is built VERY light for 3D maneuvers and cant handle hard landings from beginners. This is only what I've heard and in no way comes from personal experience.