Wordpress cannot import everything since it cannot recognize certain theme elements like slider which is theme specific. You should have at least 80%-90% content imported with the sample data. Rest of the content as with flex slider can be manually copied from the site. Please edit the page and wherever you see images png or jpg files still pointing to portfoliotheme.org, pls replace them with images in your own media library.
If you have trouble with it, email mr a temp login to your site with the details and I can help you out. Thanks