I really like the idea behind this module.
The javascript parts are really quite neat.
There are just a few drupal side things that aren't quite right.

Deleting nodes after Image Annotate is installed results in an error message.
It seems the module is attempting to delete image annotation records where nid is equal to the value of the node being deleted.
Image annotation records don't have node id field.
I guess the image annotations should be deleted one by one when the comments are deleted or the image annotation table will need a new field for node id.

I was wondering what was the thought behind using the comment system to store annotations was.
Why not give the image annotation table it's own text field?