My family and I have used Execu Car many times and we have always had excellent service. The drivers show up 10 mins earlier than the scheduled pick up time.
Even the ones who don't like to chat are still nice and professional. Not all people like to chat so I don't care as long as they are polite and professional.
The gentleman who picked us up at the airport tonight was their before our flight landed and sent text messages to alert us which airport curb door he was parked near. This was a nice touch beyond the normal procedure which is for the passenger to call when they arrive. Even then, I've never waited more than 10-15 mins. The Lincoln Town Cars are so comfy and spacious after a long flight.
I'm sad to see some Yelp reviewers had a bad experience, but that is not the norm and I would not be scared away from using this service.
It is SO much better than a shared van or taxi and a great deal for 4+ people. I would even choose them for non-airport rides; parties, date night etc.