Works very well Rated 4 out of 5 stars

Works very well, thank you.

Would be nice if I could change the default viewer/opener (ie I'd choose Paint often).

Keep up the good work :-)

This review is for a previous version of the add-on (0.2.5.1). 

Voila

To avoid tautology, please see my response to another similar comment:
https://addons.mozilla.org/en-US/firefox/addon/image-assistant/reviews/695822/