I use an online calendar for collaboration and a no longer supported calendar (Windates) for reminders and I am now trying to switch to Rainlender 2.
There is one HUGE feature both of my other calendars have that Rainlender does not:
A view of the Calendar that shows full text of all events/appointments/etc on the actual calendar page. You could call this the "refrigerator" view because it's just how people use a calendar on the fridge. You can see everything for today + what's coming up. It would be terrific if you could just click on (say) the Month at the top of the mini calendar and it popped open a full editable window showing the full text of all appointments for that month.
(I hate how google's calendar truncates the text just so the box size is the same for each day. Who cares about box size and making it pretty! You don't want to have to click again on each cell to see what's happening on that day).
Attached is a screencap of the online calendar I use and another of Windates (desktop reminder program).
The online calendar can't do audible alarms, the desktop calendar can't do collaboration. So I'm looking at Rainlenda r.