Very nice.

I'm not sure the ability to sort users by name is useful.

People may possibly be shy of showing how many times they've failed. projecteuler.net only displays the number of correct submissions for each user, and I'm personally very glad, as I can then try a variety of techniques without fear of losing "rating".

Of course, this may not be the way you wish to go, but I think many people would appreciate the option of hiding the number of failures.

In fact, if I may be pessimistic, I predict that if your website becomes popular, you will find people start opening multiple accounts in order to test solutions with one, and keep a perfect score with the other.