If free, yes. Paid not yet.
If paying, the content is VERY (no, really!) limited. Just a handful of words for each r blend, for example. Nonetheless, the animated graphics are entertaining, so if you can catch this app while it is free and wait for a major update for more continued use, it might be worthwhile.
not worth it
I think there were 4 or 5 flashcards per sound target.. Not worth the money!
Not many targets
This app has only 5 words for each context, such as initial R, medial, etc.