The specialization is the whole pitch here and it's the right one - a word list split by Medicine, Law, Business and General English is far more useful than a generic B2-C2 deck, because the vocabulary that actually matters in a client meeting or a diagnosis conversation is domain-specific. The home-screen widget format is a smart delivery mechanism too - it shows up in a moment you'd otherwise spend glancing at your phone anyway, instead of asking you to open a separate app and commit to a study session.