In its statistics, the site gets all excellent, except for the first for which it is valued as good. The site is going quite well.
Keep in mind that, before the site passes the beta phase, they need to design the site (this is done from Jin); in some cases, when there are other sites that need to be designed, a site can wait a little longer before to be declared official. That doesn't explain why the site has been in beta phase for 458 days; what I mean is that they already decided the site is going to be an official site, but work needs to be done before that happens.
When you see an announcement such as this one, given in the meta site for the site being in the beta phase, it means that soon the site is going to be graduated. As I said, soon is a relative term, but usually it means "before a month is passed."
Consider that leaving a site more on the beta phase allows the user to help managing bad questions; after the site passes the beta phase, many users lose their privileges, and they would not be able to do what they do when a site is in beta phase. In this time, the user can accumulate reputation, and be able to do more when the site is not a beta anymore.