I've used this plugin for years, mostly because it's so easy to create my own coming-soon.php to customise the look of the coming soon/maintenance page easily.
However, now that I'm mostly building child themes for Genesis the plugin won't work, I keep getting the default 'ouruts' theme not my custom coming soon page.
The reason is that in the plugin the function that calls the location of the coming-soon.php is this
$dir = get_template_directory().'/';
In a parent/child scenario this won't work - it's calling the parent directory, so while you put your custom coming soon into the current theme, the plugin looks to the parent.
To fix it I changed the line above to
$dir = get_stylesheet_directory().'/';
Should the developer ever upgrade hopefully he'll include this change, because if you change it manually as above the tweak will be lost come upgrade.