We originally booked to depart from the Hotel at 6:45 a.m. but when we arrived in Boston and learned of the time the trip took from airport to Hotel I called and changed our departure time to 6:30. The driver did not arrive until nearly 7:00 which was late either way you look at it. This was only after three calls to check on when the driver would come. The hotel had plenty of transportation options to use other than Viator, and we could already have been at the airport.
Our driver arrived at our hotel earlier than scheduled, just to be sure we would not be there waiting for him, as he said. Very courteous and careful driver, quick to help with bags and very friendly. The car was a big sedan, with plenty of legroom in the rear. We were dropped of right next to the doors into departures at Logan Airport. Highly recommended.
A great service but I think it's pointless and a lot of hassle to phone to confirm. None of the local numbers seem to work on the mobile phone so I had to rely on the hotel concierge.