The reason this app is incredible is because of what it offers, how it offers it, and how it links those two preceding things together.
I would recommend starting off with the games section. Do every problem (and there are 200 included free), and see how many you get right. What is genius about it is that the problems you get wrong can be seamlessly integrated into the notecards feature of the app. Just add all the words you dont know, learn them all, and buy another problem pack.
The SAT offers exactly the kinds of questions this app offers, in terms of vocab. Any app that offers more teaching styles besides synonyms and sentence completion is not worth your time. Most people think the way the notecard section is designed. There are words we know perfectly, words we understand but cant really define/use, and words we dont know at all. Those are exactly the three kinds of sections the notecards feature is divided into and trust me, it wont be long before there are no cards left in the "dont know" pile.
Finally, Notification Center, which in all fairness some people find to be annoying, actually works very well with this app. It can show you the Daily Word in the Notification Center, and if you already know the word then you dont even have to open the app. (Nevertheless, I suggest you do.)
Many college admissions directors are part of the older generation; that is, the generation that applied to college when the SAT was still out of 1600. Although on paper scores are now out of 2400, many people still think in terms of just math and reading. And one of the easiest ways to get that reading score up, and therefore the out-of-1600 score up? Vocab...The Daily Word