The app itself is ok for the first 15 decks if you are willing to pay $10, but if you are looking for something long-term look elsewhere. The developers want to sell their main Brainscape app, and that requires an expensive subscription if you want to go beyond the 1st 15 decks... Read the reviews of the main app to get an idea of what you are getting into.
As far as vocabulary apps go, this is one of the better ones: the nouns are presented with the article, the pronunciation is given, adjectives are shown with both genders, where different. Also, most of the words chosen are relevant. What I would improve are removal of some of the words, such as the personal pronouns, and teach those as part of a different app all together in one go. Also, sometimes a hint on which meaning of a word is meant would help. For example, the app just shows "mean". Is that supposed to be "cheap" or "not a nice person"?
I also feel that for the $10 there could be a few more word lists included, but at least the app allows the first 3 vocabulary lists to be used for free to evaluate if the approach works for you. I think the key here is self-discipline and honesty to oneself, otherwise this approach wont work too well.