I've never rated anyone but I have definitely used that site, as well as opinions from friends, to help me decide who to take and who to avoid if at all possible. So far it hasn't let me down either way.

I need to use it for that purpose more. I rated my first professor on it today. I despise him. He inspired me to use the site, really. 8P

To feel right about it, though, I'm going to attempt to rate every professor I have after the term ends. The website is a little biased, otherwise, you know? Even though most either all love or all hate a professor, only having extreme ratings doesn't help as much as seeing what the average would be if enough people who felt the professor was somewhere between the extremes would add their ratings too.

That was a mouthful. Bedtime.