I have NEVER understood the need for such cameras, particularly and moreso today in the modern age of digital cameras...
Here's the basic difference: Instax mini cameras will produce a one-of-a-kind photo (way over-priced) and you cannot easily make copies for friends and family. Also, it leaves a lot to be desired in terms of focusing. And the cameras are built so chintzy... but, in the final analysis, it's YOUR money and you can waste it any way YOU want... or spend it wisely, if you so choose to do.
Meanwhile, for a little more, you can buy a point-and-shoot digital camera and see the image almost instantaneously on its monitor; with little effort, you can forward copies of any image you take with the camera to anyone via email... and you can even get hard copies made from almost any large box or even any neighborhood pharmacy or large "big box" variety store at affordable costs, in any size. Can you figure it out?
WHAT happens when the "novelty" of using those chintzy toy cameras wears out and you calculate how much you've spent throughout the years you used it? You DID ASK if it's worth it, yes or YES? Well, it AIN'T worth it.
STOP being a member of a herd, following trends like others; be a trailblazer and think for yourself, save money and buy other worthwhile things.