I like that they do the work for you. I could read all the ingredients on the back of all my cosmetic bottles, and google what they are and if they're okay but that would take forever. So I find this website to be super awesome. I just check out the score, then scroll down the page to read which of the ingredients (if any) are harmful and why.
So here is what I'm looking at today:

Skin Deep score: 3
After reading what they had to say about my product, I searched for 'tinted moisturizer' to check out other brands. Some had a lower score which is cool, now that I know this I might try those next time. But I'm not too concerned with a score of 3 when Neutrogena and Olay make some that score 7 & 9.