Actually this could be bad advice in the new model. You see the App Store search is still at its core just a Lucene index. In which case the weightings are likely to be similar:
As you could see just stuffing keywords will guarantee you appear in lots of different searches but not necessarily ranked highly in any of them. Really depends on the type of app you sell.
titlePhrase 9 / authorPhrase 9 / subjectPhrase 9 / genrePhrase 9 / titleWords 3 / authorWords 3 / subjectWords 3 / genreWords 3 / titleExact 20 / authorExact 18
As you could see just stuffing keywords will guarantee you appear in lots of different searches but not necessarily ranked highly in any of them. Really depends on the type of app you sell.