The keyboard on my iPad does not match the Turkish alphabet. For example, there are two forms of "i." As a result, when you type an "i", the app may interpret it incorrectly and ding you for a wrong answer. This gets annoying pretty quick. If there is a way around this problem, I have yet to find it.
Otherwise, the app works pretty well - although it sound have a dictionary.
Bikingbaker about Babbel – Learn Turkish