I am brand new to this site today, but I have found it frustrating that someone asks a question for which I have a good answer, but I'm unable to answer the question as someone has put the question of hold for not being specific enough.
Not all questions are suitable for this site, or Stack Exchange sites in general. As a result they will be either put on-hold to give the poster the opportunity to bring the question more on-topic for the site, or they will be closed off and / or deleted if they are unable to be made suitable.
These questions are closed because we're more on the strict side about what can be posted. It means that the overall quality of posts on the site is generally very high (unlike sites such as Yahoo Answers or Quora who have a free'er approach to content).
The aim being for this site (and other Stack Exchange sites) to become a repository for common (and less common) User Experience questions and their solutions. Problems that it is likely other people will have had, or will come across in the future. Hence why questions like "please review my UI" don't work here, as they're only ever going to be relevant to that one person.
Closer to Wikipedia than to a discussion forum or blog really.
It's probably useful to take the site Tour to get an overview of how this site works, as it's a bit different to traditional forums / bb's etc. Hopefully it'll help out and you'll be able to jump right in an start solving some of the current, or even the unanswered questions that we have here!