As I almost solved all of them, I give my impression on the site:
1)
There are some guessing at some points:
realistic 2: The exploit is well-known but not simulated (meaning there is only one possibility and it's in lowercase).
Javascript 6: A little bit weird: You need to apply the hint on the solution directly.
2) I think some challs have not enough hints:
Crypto 1,5,6,9. & Trivia 2,6.
Challengeland seems to be out of order. If you click on the link, it says that this domain has expired.
I don´t know if this is only temporarily, but maybe Challengeland should be excluded from the listing.