Age My Face is a face editing and filtering app for the iPhone that doesn't use the same automatic-style filters that other apps in this category use. While the resulting images can sometimes look as advertised, it's a lot harder to achieve the intended result when you are forced to do the vast majority of the filtering, manually. Combined with limited options in the free version, it's not the best example of a face filter app.
When you open Age My Face, you can select a photo from your library or take a new one with your camera. From there you can start applying filters. The app will provide a number of "masks" that can be laid over the face in the photograph. You can change the transparency of the image or move it around until it fits just right -- this process is relatively straightforward and allows you to do a lot of customization in the image, but the masks don't always fit quite right and often still look like what they are -- masks. There are other features, as well, like beards, glasses, and hats; and while some are locked pending a paid upgrade, there are enough to be useful. But because of the manual layout, it is hard to make them line up just right so the image looks natural.
The interface in Age My Face works well to display all of your options, but because of the lack of coordination between the filters and the manual application of those filters, the app can be frustrating to use. If you enjoy playing with these types of hands-on free apps, this is a decent but not great option. But if you prefer an automatic filter, look for a different app.