On Area 51, the site appears to be in the "healthy" ranges for everything but traffic and user count.
I think those metrics are for the beta overall, not just the private portion thereof (because the user count metric is basically impossible to hit unless everybody invites a lot a people). However, they appear to be the most obvious measurable issues with the site right now.
Beyond those metrics, on a more subjective note, I would say that the most worrying aspect from my perspective is the large percentage of questions which seem to be either plugin recommendations or simply already on-topic at Stack Overflow, Super User, or another StackExchange site; these don't do enough to distinguish a dedicated vim site from others, especially given that that overlap has been the primary rationale for shutting down vim sites in proposal stage before.
We've had no official indication from StackExchange itself about the state of the site.