I've been following Jason's work very closely with Leeflets and Dropplets. The simplicity of the system can be far superior to WordPress when doing small-scale sites. I love that he's taking this approach into WordPress.

The area where WP fails to excel is allowing easy customization of the admin. No one wants to keep up with the constant change. You can almost guarantee that any plugin you write that does things in the admin will break with the next update of WP. Maybe it's possible to get around this by simply removing everything possible and adding just the things you want.