Square FX solves a problem many people have when uploading pictures to Instagram--the fact that their pictures are generally cropped to fit the square frame. While this doesn't affect all photos, it can have a negative impact on quite a few, and Square FX allows you to resize, refit, and avoid cropping images before they go to Instagram, albeit with limited additional features.
While Square FX does everything it promises quite well, it lacks enough features to make the trial truly useful as a supplement to Instagram. When you first open the app, you can choose an image and drop it into one of a handful of square frames that allow you to avoid cropping that image. From there you can change frame colors or style, but you'll notice that a large percentage of the apps' frame options are locked pending an upgrade. Another issue we found was the sharing function. When finished, you can save the image to your library and open Instagram, but it won't actually export the image into Instagram or save it directly. This creates numerous extra steps that most people won't want to go through.
While Square FX works as advertised, its tight trial restrictions, limited sharing options, and lack of additional editing tools leave it lacking.