Uber is also available in Thailand too. For now, just in Bangkok, but you will be lucky if you can catch one of these as they are too few yet.
The price starts at 25 TH and increases 1 THB per minute and 4.5 THB per kilometer. That is sometimes slightly cheaper than normal metered taxi, but be careful because it is kind of tricky. The minimum cost per ride is 45 THB and there is also a 45 THB fee if you cancel the ride. That is for UberX, the cheapest one. UberBlack is more expensive, as you can see in Uber website.
In most cases Uber will mean a more expensive ride than on a normal taxi, but in exchange you are supposed to get a better service.
One thing that you might and might not like is that you need to add your credit card details first when you create your account. The service fee is deducted automatically from your card, so you don’t need to carry cash with you. That’s good, but it is also kind of scary somehow.
You can get an estimation for the ride cost on the app and the website, but be aware that some routes have a fixed cost, like 1,000 THB for an airport ride.