When comparing Evolution vs California, the Slant community recommends Evolution for most people. In the question“What are the best calendar apps for Linux?” Evolution is ranked 3rd while California is ranked 7th.
Ranked in these QuestionsQuestion Ranking
Pro Great integration with Gnome environment
Pro Manages contacts, tasks, calendar and memos as well
Pro Good support for Google's services
Pro Supports exchange servers
Evolution is one of the few Linux desktop e-mail clients that's supports exchange servers.
Pro Clean interface with 2 layout variants
Going to View > Preview has the option of switching between "Classical View" and "Vertical View".
Pro Integrates with the desktop in order to provide notifications
California offers desktop notification on most major DEs in Linux, which is great to know when events are happening while not having to have the app open in the foreground.
Pro Events can be added using natural language
The application allows natural language input for events. For example, typing in "Lunch with Stuart Kearney at 2pm" will set the appointment.
Con Can't choose different settings for each mail account
Settings have to applied to all mail accounts.
Con Currently not in active development
Yorba, the group that developed California, is no longer actively developing software.
While Geary (Yorba's mail client) has been adopted by the elementary teams as "Pantheon Mail", both elementary and Gnome have their own calendar projects and it is unlikely that either of them will contribute to California in the future.
That being said, California uses evolution data server for all backend/sync/storage related tasks, which should hopefully make it possible to use it even if 3rd party vendors change their APIs/protocols etc. As long as EDS does not introduce backwards incompatible changes or any major California bugs occur (it has been working fine for me so far), the current state of California should remain usable for quite a while.
Con Currently no drag and drop support
There is no way to drag events in the app for easy switching, it all has to be done manually which can be a lot of work to move many things around.