OK, just got the chance to test it. It looks great in general and needed just few minor tweaks to output proper HTML code for use with SmartMenus jQuery + Bootstrap addon. I did the changes so just get the updated version from here (apart from those changes it’s identical to the original code):
https://github.com/vadikom/wp-bootstrap-navwalker
The only other thing you may need to tweak is the depth
parameter if you have more sub menu levels – e.g.:
wp_nav_menu( array(
'menu' => 'primary',
'theme_location' => 'primary',
'depth' => 3,
// ...
Cheers!