This app is off to a good start introducing most of the initial sounds of mandarin in combination with the finial and vowel sounds. However, you cannot search the sounds by finial/vowel sound. Additionally, some of the phonemes and syllables do not have a corresponding recording to play, which seems just to be an app error.
There is no feedback ability in the app so whether or not you are accurately reproducing the sounds is not measured.
The best aspect of the app is the animated visualisations of how to move your mouth in order to produce accurate sounds. This is very useful. However, in order to use this resource fully you must pay the in app purchase fee of 9.99. I am looking for an app to help my husband learn Mandarin. It's too bad it doesn't seem fully realised yet.