Those looking for sets can easily implement it within the plugin with a bit of logic.
Around line 146 of flickr-photostream.php in the plugin use a different function.
$photos = $f->photosets_getPhotos(72157633896989722, NULL, "description", $max_num_photos, $l_flickrpsp);
use var_dump or print_r to look inside the returned array, or better still
The elements of the array are named differently so then you will have to use ['photoset'] in the subsequent arrays.
if(count((array)$photos['photoset']['photo']) == 0) return(__('<h1>No photos</h1>', 'flickr-photostream'));
it should be possible to add this into the short code for use without too much difficulty.
Wonderful plugin gives excellent results so congratulations to the author.