I used to love double-crosstics in the NYT and magazines, and Ive been very happy to find and enjoy this app over the past year. Being online and able to easily delete a whole clue answer permits a much more fun approach to the puzzle than doing them in ink on paper.
I too was frustrated that I seemed to be stuck in limbo for several weeks, unable to complete the purchase of Books Ten and Eleven, but just now I tried buying the Headlines for the first time. There was a new AppStore purchase agreement I had to OK, and then suddenly the floodgates opened for my other failed purchases in this App.
PSMCN about Crostix, v3.2