The different event views in KOrganizer look a bit dated, the painting code could use a bit of updating to make it look more modern.
* use softer colors (the default green for events does not look very good, something softer, less intense color would be better)
* make the events rectangular (remove the round corner, or notably reduce it) - this needs to be done carefully otherwise, it may not be easy to distinguish between multiple separate events and a single event spanning multiple days (there was some work done previously in D6368
* make the day/hour lines less outstanding
* remove the rounded corners from events like in month view