I asked a similar question at the beginning of the beta: what is the scope of WordPress Answers, and how does it differ from the existing sites? Are there questions that we allow, but are not allowed on the other Stack Exchange sites?
I was hoping for more participation, but judging from the answers I think we will allow some questions about WordPress.com, which is now explicitly verboten on SuperUserexplicitly verboten on SuperUser. Also questions/recommendations about themes or plugins seem to be acceptable here, and probably not on other sites.
So currently I think WordPress Answers adds value to the Stack Exchange network, because it allows questions others do not. But if we want to keep the site grow, we should attract more experts. This requires more promotion, and better pruning of low-quality questions.
Also, I think it would take a while before they close a site Joel used as an example of the excellence of the Stack Exchange system!