there is a bug in the shortcode handling. It is a functional problem, not a coding problem. The function isw echoing instead of returning the output so the gallery is diplayed at the top of the page content instead of the exact place of the shortcode.
I made a quickfix with output buffering:
$gllr_options = get_option( 'gllr_options' ); (about line nr. 809 in gallery-plugin.php) I inserted
and at the end of the function (around line nr. 889) I inserted these two lines
$gllr_output = ob_get_clean(); return $gllr_output;
It works well, but maybe you desire another solution.
Anyway, I love the plugin, it is simple and clean exactly what I prefer.