Here's the first and most important thing: if you're looking for a car service that meets you at the airport holding a sign with your name on it, this isn't them.
Tel Aviv operates like this: when you land, and after you get your bags, you call them, and they send a car. They often have cars in the area, circling nearby, ready to pick you up - but traffic in the airports are terrible, so there is often a wait. You have to bring all your bags to the curb outside the terminal and wait there.
However, if you are willing to do that, they have decent prices and most of their drivers are decent - but not all of them. One of their drivers did get WAY lost on my once.