Last time I tried, Geary was so feature-incomplete that I had preferred facebook chat over
it. Does it have GPG integration now? Filter support? A solid secure network stack? Does
it clean unnecessary mail headers as does Evolution? Does it integrate with
evolution-data-server to make gnome-contacts and the gnome-shell calendar work? Those are
just the basic questions/requirements to replace evolution by default.
Still, the most important question: Is it actively maintained so we can expect fixes for
security bugs and major crashers within a week or two?