Here in Germany, as other posters have mentioned, they are standard for young children. I only tend to use them now when the DCs have a tummy bug where I am unsure if they will keep the medicine down.
One thing that a nurse told me however, is that oral paracetemol is better for sinking a high temperature as it is gentler. It is more for the body to cope with if the fever is spiking up and dropping suddenly after using suppositories.
Once you get used to it though, they are easy to use, warm them in your hand before taking them out of the packaging, a bit of vaseline and be gentle but firm.