Wordpress XML import Docs
A statamic addon to import Wordpress XML files
It's quite simple really. Install the addon, and you'll get see a new tool called 'Wordpress import'. Upload a WP XML and the addon will do it's job. It will overwrite existing files, except for existing users.
It's far from perfect as transferring content goes, but you should have a good starting point for your new site. After using the tool you should further tweak the content using search and replace.