Right now it's easy to see if an image is favourited, approved, rejected. I might be missing something, but it's harder to see that an image has been commented on; I think you have to open the image, and click the comment button, before it's apparent that there are any comments?
Would it be possible to have a comment symbol on the thumbnail of an image, or something to show that there are comments? And perhaps when you've double-clicked and are looking at an image, if there are comments, highlight the button in some way or put the number of comments in the button?
There's another enhancement about marking comments as completed or hidden; maybe the annotation should show the number of un-completed comments?
Maybe having a filter along the left to hide un-commented images?