I am a consultant and I travel often.
They not only sent an emailed confirmation, but they called the day before to remind me (My details had changed and I was very happy they had called b/c I forgot to update them of the changes). And after the trip I had an electronic receipt emailed right to me.
I have since used them in Chicago and even in London (England). And each time the chauffeurs knew what they were doing and had my beverage and local newspaper waiting for me in the vehicle.
They say they can offer service in over 600 cities worldwide, and if they're this good so far, I will definitely use them for my several of my upcoming meetings.
Pros: They have been professional!