It does not start until May 5th, so we won't have anything concrete until then.
A frequent poster on the Transportation Board (CarolA) did get to test the baggage check in part of ME last week or the week before. If you search for her user name, you could find the thread.
The busses are not running yet, but she was able to check her bags at her resort, and they DID IN FACT make it to her home airport.