Personal information managers (PIM) are the major influence on most people's opinion of a desktop. When you launch an application, the desktop is simply something to move past as quickly as possibly.
Similarly, a desktop's system administration tools are used only occasionally -- and many of us still prefer to use the command line. By contrast, a desktop's PIM tools are used daily, and switching to new tools can be disconcerting.
This basic fact was rammed home for me when I recently switched from GNOME to KDE on my main computer. I had little trouble learning my way around KDE, and I continued to use many of the same programs, such as Firefox and OpenOffice.org.
But moving from GNOME's Evolution to KDE's Kontact -- that unsettled me. I correctly anticipated that most of the features I wanted would be there, but I didn't know where they were, and some features were new to me. I couldn't ignore the differences because I faced them dozens of times each day.
However, the experience made me think about the differences between Evolution and Kontact. Both are mature PIMs, with most of the features that ordinary users might want. But before long, I was keeping notes, and consciously thinking about the differences. The interface, the applications for email, address books, calendars, tasks, memos, and other features -- I looked at them all closely.
Was there any reason to prefer one over the other?
Since Evolution had become familiar over five years and Kontact was part of the new desktop I had migrated to, I had no existing preference, so the results surprised even me.
Like most of GNOME, Evolution has a minimalist industrial look. It consists of five modules: email, contacts, calendars, tasks, and memos. None of these modules looks as though it were designed with much reference to the others, although sharing information between them is reasonably straightforward.
By contrast, Kontact still retains much of the informal look of KDE 4. In addition to the modules found in Evolution (some differently named), it includes modules for RSS feeds, popup notes, and tracking the time to do each task. All its modules have their own names and can be run without Kontact, but go mostly unnamed within it. The design throughout all the Kontact applications is more consistent than in Evolution's, which reflects the greater unity of appearance in KDE than in GNOME. In addition, because all the applications depend on KDE's PIM engine Akonadi, they tend to open faster than Evolution's, too.
One useful module in Kontact is Summary, which lets you see at a glance what new messages you have, as well as upcoming events and deadlines. However, in other places, Kontact is less user-friendly than Evolution. In particular, settings such as email templates and the default names of message filters are written in pseudo-code that might intimidate inexperienced users. Nor are inexperienced users likely to know the distinction between Ham (wanted mail) and Spam that appears on the icons.
Both Evolution and Kontact can be extended with plug-ins, and other applications can be written so that they can be launched from within Kontact. By contrast, Evolution's plug-ins tend to be extensions that add a single specific function.
With either PIM, you can import information from other applications. Evolution includes the ability to import from Outlook, but in general supports a limited number of programs, although you can always use standard formats like vCards and CSV files. Kontact has the advantage of being able to import more formats, and includes wizards to step you through the process. Neither Evolution nor Kontact directly supports importing from the other one.
Verdict: Tie. The choice of widgets tends to be personal, so neither has a clear lead in general design. While Kontact has a small but definite lead in speed and design, I have known some people to reject it because of its general appearance.