I recently started using Rainlendar in conjunction with Google Calendar and I have found Rainlendar very useful as a desktop calendar program. Unfortunately I do have some problems with the user interface that I think should be improved upon if there are future updates:
1. The calendar interface is not intuitive.
I think Rainlendar would benefit greatly if it had the calendar view equivalent to the manager window. Something that is similar to the way other calendars allow users to view a week, day, or month and also read the events in at their scheduled times in those views.
2. I cannot double click on a day on the calendar and enter an event (though I can right click).
3. The ability to edit the interface for event lists, task lists, and the today list is too limited.
Some windows can change width, some can't and it is confusing. I suggest making one user there that allows heavy customization and making that the default. Shadow4 is probably the closest to something like that.
4. The alarm is terrible and limited.
The alarm should be a manageable window and not a popup. The snooze and dismiss options should be improved so that users do not have to manually input each amount for snooze time. Also, if there is more than one item in the alarm it tends to reset itself and chime again. I think there are many ways the alarm can be fixed (could be similar to Thunderbird or Efficient Calendar)
I enjoy using Rainlendar because it has some great features, but I would like to see the things mentioned above improve if improvements are ever going to be made to the software.