I just really used it for the first time with a bunch of sme's testing, instead of me just playing around with it.  
A few thoughts.  I wish that instead of resolving All comments attached to a slide I could resolve them individually.  Especially if there are more than one person reviewing it.  I could have 10 comments, but only 3 I will be resolving.  Or if I could "reply" to one comment with an additional comment or tag with an emoji that would be helpful too.
Another feature would be great if one could annotate a slide image, but might be too difficult as the course is (seemingly) running on the left of the screen.
One more thought, I would love some option to know how many people opened the review to look at the course and didn't comment.  I sent it to 5 people and only 1 had any feedback, did the others not look at it, or did they look and just not comment.
I do like the emojis for the purpose that I have been using a select few as comment coding options.  Example:  A green heart is a comment I will resolve once the review process is over.  Orange diamond  is tagged to something I need to research more.