Some of our users are experiencing issues with the latest update (1.5.3) and the iCloud sync. In these cases the app crashes during the sync. If you’re having trouble, please disable the sync. We have a fix (1.5.4) already pending at Apple and it should be live within 24 hours. Then you can enable the sync again. Sorry for the inconvenience.
Update: Version 1.5.4 is live, please update.