It's okay
The pronunciation of the r controlled vowels sounds odd and not American. This gives good practice of short words and vowel digraphs. It becomes more engaging as a person progresses moving to making words.
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Phonics Tutor 4 appears to be a legitimate app. AppsHunter Legitimacy Score for Phonics Tutor 4 is 80/100.
Based on 80 of 100 points across 7 verification signals from App Store and developer data.