The Mirror is a very straightforward app -- it's a camera with a mirror framing your face, a la Snow White. You can take photos in the mirror, take video (oddly without the mirror and limited to only 30 seconds), or you can save and share your photos and videos with other users through the app's menus. It's not particularly robust, but it does work quickly and effectively for what it offers.
The Mirror is an app that doesn't try to do too much and as such it succeeds in performing these few functions very well. The mirror overlay works well for photos, and resulting images look good. The video tools are odd in that they remove the mirror from the screen and limit video creation to only 30 seconds, but this also works well and sharing of both images and videos is fast. Menus load quickly and Facebook sharing is built into the pop-up menu for quick and easy exporting. Without editing tools, however, and without options for how photos and videos are formatted and taken, the app limits a lot of what you can do.
The Mirror is a feature-light app that works well for what it offers. It's fast and effective, however, so if you want to take framed photos with the mirror motif or snap and share short videos on the fly, it will get the job done.