The error people are getting is:
We're sorry, but we are unable to serve your request at this time.
Please try back in a few minutes.
Personally, I have no problem accessing it, but it seems like many are having issues.
The issue has been reported back on September 24th and it still is an issue for many, even today. On October 1st, Google Maps Guide Jen said, "Thanks for bringing this to our attention; we're looking in to it right now." But even since then, many still are reporting issues accessing the Google Local Business Center.
There is no ETA on when the issue will be resolved for these users. Nor did Google explain what the issue may be.
Forum discussion at Google Groups.