Taxi drivers are a funny breed. In developed countries, drivers are usually cab driving "between´ other jobs. Pity many of them don´t do this particular job all that well. However many do. I have had some of my greatest conversations in taxis. More tips, especially if you should ever find yourself in trouble….
If you don´t speak the language make sure you have a note written by your contact with the address and directions on it. Show your driver and make sure you know if you are in one of those countries where a nod actually means yes.
If the taxi takes you somewhere else, it may be a misunderstanding, not a hijack. Leap out at a red light and toss money on the seat (just in case you are wrong).
If you need to leap you will want your luggage with you. Keep it on the seat next to you, not in the boot. If you realize you are in serious trouble, leap anyway. You are worth more than your luggage.