I think it's a great idea. I would rather a set of tutorials though. I don't want to email and waste somebody's time if I'm not able to commit to anything.
Actually, it's processed by a script (a bot if you like), however, if something fails a person replies to you. This is the problem with many of the challengers. When everything is ok they proceed, when something fails[1] it might take weeks to get a reply.
[1]: failure might be because of a corner case or an implementation not working on a specific configuration.
I liked the Matasano Crypto Challenges, but this was less informative. It's a list of tasks, not a tutorial. There weren't pointers to resources, either.
I'm running through these at the moment. Some challenges have really heavy queues (ie: Challenge 3 has an expected response time of 1 month at the moment. ~8000 challengers are participating out of an expected < 1000).
I agree - I really like it and I'm learning a lot. However, i'm losing motivation due to the lengthy queue.
Task 6 currently has a two month wait. Given that you may have to submit multiple times to get feedback and fix mistakes, you're talking a significant part of a year to get a single task done.
I understand there's a massively unexpected surge of users, but I'd happily donate to help improve infrastructure (if donations were ever available)
Inspecting HTTP headers gives a hint: Last-Modified: Sat, 22 Mar 2014 04:33:36 GMT