I had bought some journaling applications, but never started to use them for more than a few days. Since buying DayOne, I have been using it, since it is very pleasant and easy to use: what is amazing is that, in some way, the app itself convinces the user to keep a diary. It is simple to use, and perfect sync with iPhone and iPad.
There is only one significant thing that is missing: the ability to export pictures. Nobody can ever be sure that an app will last forever (I have seen good apps discontinued), and the content of a journaling app should not be captive. While the export of text works nicely (and the explanations of the developer have convinced me that Markdown can be a good solution), the inability to export pictures is a problem: I would like to include pictures sometimes, I started to do it, but I gave up after the first few days, since there is no way to export them.
Once this feature is added, I wll gladly give five stars to this app. In the meantime, I consider it as a very good and highly recommended app, but not yet perfect.