It can be used by those ones who just started to learn the language since it gives basic information.
The bad thing is that you need to subscribe to the application to download its content and you will be charged automatically in set periods of time. Even if you dont use the application. So be careful ! Before deleting it you must cancel the subscription. The ways to do it are described on the web site (but not clearly enough)
Eugeny Beck about Babbel – Learn Turkish, v4.3.3