I've only been using JIG for a short while, but I already love it dearly. Every time I think about a minor detail that could use a tweak, it turns out that there's a setting or css I can change to make the gallery look just the way I want.
I had a minor issue with the combination of SiteOrigin Pagebuilder/NextGEN Gallery and JIG, but I managed to solve it (when JIG is set to "take over" all NextGEN shortcodes and all previously created NextGEN galleries, SiteOrigin Pagebuilder breaks down and just displays the original Nextgen shortcode instead of a gallery. Fortunately I was early into the site development and was able to swap all NextGen shortcodes for JIG shortcodes, so it all works fine now). I'm looking forward to launching my site :)