Only "downside" is that editors of items will have to deal with shortcode; simple enough though.
The support I bought with my subscription was fast and polite.
The plugin says it integrates with K2. That integration is not as useful for me as I hoped. The only thing it does is let the author of an item upload an archive from which a gallery is created. It's not possible to point to a previously uploaded folder on the server. For that, the author would have to use the shortcode, like in the free version. Also, the shortcode and the upload function will use different image directories on the server. If I change the shortcode's image root path, I'll have to move my imags away from my central image folder into media/k2/something, a path that will also show up in my source code. If I don't, I'll end up with a fragmented image collection.
The value:key pairing to write into the shortcode is laughable. I'm supposed to write "image-folder:::::2::" to achieve a certain effect - sorry but no.
The thumbnails can be displayed in a few different modes, all very eye-candy-like. Needs a lot of CSS overwrites to get it to look decent.
Again, it does what it says and appears professional, it's just not a very good plugin, in my opinion.
I reverted back to the tool I wrongly thought I was buying, which works much better overall, has more features, looks better.