|Property of Andy Field. I certainly can't take credit for this.|
1) The aesthetic is priceless. For example, his intermediate statistics page begins with the introduction, "You will experience the bowel-evacuating effect of multiple regression, the bone-splintering power of ANOVA and the nose-hair pulling torment of factor analysis. Can you cope: I think not, mortal filth. Be warned, your brain will be placed in a jar of cerebral fluid and I will toy with it at my leisure."
2) It is all free. Including worksheets, data, etc. How amazing and generous. And, if you are feeling generous and feel the need to compensate him for the website, he asks that you make a donation to child-welfare organization. Or you could buy his text book.
3) He is a psychologist that teaches statistics, which is different than being a statistician teaching statistics. Many of his examples are psychological.
4) Another thing I like about this site is that he has plenty of SPSS examples. Most of the texts I've reviewed have Excel, Minitab, various TI calculator instructions, but not many integrated SPSS examples. Not only does he provide data, he also provides some jing/video tutorials.