This has a much better interface than a similar app, Open Any File—and without the nags to try other apps. The two have similar icons with the same green and gold color. File Opener has a unified interface which makes it easy to see a preview, file properties and available apps at a glance. While you can see the same information with various built-in features of the macOS, File Opener consolidates the information in one window. Certainly a good value for the price.
What it lacks is a drag and drop interface which would add to its utility. It uses the conventional file open dialog, which isn't bad, but drag and drop has it's advantages. An example of an app that has both is Pacifist, but of course it's been around much longer—and it's no longer free.