> Is it pretty easy to pick up?
I thought so.
Concrete isn’t a “lightweight alternative” to WP, though. Just like WP, it’s as heavy as you make it (add-ons, custom code efficiency, etc.). I’m not a heavy WP user (not a heavy Concrete user, either, really), so I couldn’t compare the two performance-wise.
Having said that, however, I don’t think either would be “overkill.” Concrete feels more “basic” (in a comfortable way), has an active dev/support community, and is fairly intuitive to use.