It's like magic. You push a button and a photograph shoots out.
Instax mini 7S has only few settings, so there is no technical stuff to slow you down. Pick one of the lighting settings from sunny to shadows to indoors, point the camera at something interesting and shoot. A child could use it.
Loading film is very simple. The Film is a just a little rectangular box you slid inside the camera. It only goes there one way so its hard to mess up. The film has 10 shots in it. A packet of two films costs about 12€. The photos have the instant "polaroid" feel to them, but they're not square. The tall thin calling card shape is refreshing. (If you'd like to have a square shaped pictures there Instax 210 with wide film)
Its nice to have "real" photos you think before you take instead the tons of digital pictures buried inside your computer or phone.
Best pictures are taken in a semi sunny weather. Too bright and the colours can sometimes get faded or there's a hard contrast between light and dark. On dark evenings get the flashlight look of ghostly faces, because the flash is automatically always on. If you wish professional level photos with perfect quality this is not a camera for you. But I myself like this "alchemistic" feel not knowing exactly what the picture will look like. That's the whole point :)
Also there are lot of weird photographic projects you can do with your instax mini. Its cheep enough to do some mad science. You can do double exposure by pulling the film cartridge slightly out before the photo shoots out. You can wrap the camera in a see through fabric to get interesting "filters", use a strip of different coloured films over the flash to change it. Or maybe use the photos as material in cool DIY mixed media art things... Get creative.