I have used their airport transfer services three times, actually twice though because I cancelled once.
The airport transfer from home to Newark was good. On time pick up, nice driver, and no discrepancy of fee.
But the airport transfer back from Newark at night was bad although on time pick up. Once arrived home, I was told a higher fee than what I was told at the reservation.
The service that I cancelled was bad, too because of delayed pick up by 30 minutes at the airport.