Only part way through the hiragana so far, but picking it up quickly... much quicker than when my grandpa tried to teach me with just flash cards! Each lesson gives great tips on how to remember, and my favourite part so far is quizzing on actual words. I am experiencing the random crash as well, so hope that can be fixed. Another suggestion would be turning off the sound during the quizzes, so that it forces you to phonetically read the word before associating it to the meaning, rather than just hearing it.
willpower604 about Hiragana and Katakana-Japanese, v1.2