I don't like rectangular pieces. I want my puzzles to be like jigsaw puzzles and since there are already good ones on the market, don't see a need for this one. I like the Android-based "Jigsaw Puzzles for Adults" by Veraxen Ltd. which you can also get on Windows using Google Games program. It's got enough free puzzles to satisfy the casual user, and paid packs of puzzles for those who need more, with no ads interrupting your play. You can also specify difficulty level in number of pieces per image. And no, they didn't pay me, I just like to spread word of good programs.