Not being able to add events is unfortunately a deal breaker for me. That means I need iCal/Google Calendar for adding events, and adding implies planning/browsing.

Generally I think digital calendars can be made much better, almost to the level of being the basis of an operating system gui. Searching and visualising for instance e-mail could be visualised in a calendar's month view. Weather is a given. Or viewing a git repo root in month or week view. Also keeping track of computer boots and reboots, or when a certain application was installed or updated, or when my computer went to sleep and when it woke up.