So Ive had this for awhile now, and it is honestly one of my favourite apps. Its super great that you read all the reviews, too! The notifications can get a little weird or creepy... But that kinda adds to the awesomeness.
So one suggestion I have is a lunar calendar? I mean you can select the date, but only on the gregorian solar calendar.
Nathan Lamarche about MOON - Current Moon Phase, v7.0