Gett - Taxi for iOS aims to be an Uber clone. However, the service area is severely limited. If you fall within one of the covered markets, this might be worth looking at; but Uber is still your go-to service if you need a personalized ride.
Gett - Taxi presents in portrait mode to reveal a very simple and pared down interface. It's hard to call the app intuitive or modern, since it's little more than a GPS map with a few input fields. You'll need to setup an account to use the service, but the process was fast and easy. There's even a credit card scanner that streamlines the process of entering a payment method. Just take a picture of your credit card, and you're good to go.
The GPS maps rendered well but were often sluggish and caused shoddy behavior throughout the app. To schedule a ride, just input a pickup address and drop off destination. The app will let you know what cars are available in your area, and how much the ride will cost. Alternatively, you can just let the app detect your geographic location via GPS, then enter a destination manually. The app will let your know if you live in an unsupported area, which for this continent, is anywhere outside of New York. I'm confident the developers have plans to expand coverage throughout the globe, but for now, service is extremely limited.
I planned a trip from a random point in Manhattan to JFK airport, and the estimated cost was well over $200. At those prices, are you sure you want to use this app over just flagging down a taxi?
Gett - Taxi seems like a decent service, but at this juncture, I'm hard pressed to see why anyone would use it over Uber.