we just got back last week, and also used tiffany.
i was very pleased. the driver met us in baggage claim and helped with the luggage, which was a huge bonus since i was traveling by myself with my two young kids. we were the first from our flight to arrive in baggage claim, and he was there waiting! i paid him cash for the round trip, and only realized later that i did not get a receipt or voucher or anything for the return trip. that made me a little uneasy, something i would normally NEVER do!
i started to get worried when the (different) driver was about 15 minutes late. but when i called, they assured me that he was on his way, and he pulled up a few minutes later.
all in all, my experience with ttc was very good, and i will definitely use them again!