Can I work on multiple devices?

Currently there is no sync available i.e. ideally you should have the data on one machine. However if you follow some rules you should be able to use the database on a shared storage like Dropbox and maybe iCloud. These are:

1. Never run the app on more than one machine at the same time
2. Make sure you really "quit" the app before opening on another device
3. Make sure to always have backups of a previous state in case something went wrong e.g. by using Time Machine or creating copies

This is indeed just a work around. Implementing real sync has top priority on my todo list, but it is a complex task. Therefore I cannot make any forecast on when it will become available.