Driver was good - make sure you call viator a day or two before you need the ride to the airport to get the time/location down correctly - we had our guy show up too early but overall great.
Transfer was averagely priced at around £44 each way, comfortable, private, however this excludes toll which is $8 and tips. We also gave a $5 tip to which the driver huffed and stated the toll is $8, we feel this was very rude as it clearly states tips is at the customers discretion.
Both the pick-up from the airport LGA to our Manhattan hotel then back to the airport 3 days later went well. Each car was fine and the drivers did well. I would use this service again.