Works pretty well, but for some reason the context menu doesn't always offer the rotate image option. In the situations where context menu doesn't offer rotate image, Firefox still knows I am right clicking on an image because it offers open image in new tab in the context menu.
Also, I know developer is minimizing impact on context menu, but I think I would prefer 2 options in the context menu instead of 1, rotate clockwise and rotate anticlockwise would be nice, to prevent having to rotate 3 times sometimes to get the orientation correct.