The thing nobody tells you about non slip rugs is that the grip wears unevenly before it wears out completely. You'll be a year in, feeling smug about the whole setup, and then notice the back corner near the door has gone slick while the rest still holds like the day you bought it. That's the bit that walks over it twice a day, drying out and getting stepped on at an angle, and it's the first sign the backing is on its way out, not a flaw you'll spot in a showroom.
A well made one has a proper rubber or dense latex backing, not a thin spray coating that flakes off in gray crumbs the first time you vacuum it. Run your thumb across the underside before you buy. If it feels tacky and slightly textured, good. If it feels smooth and shiny, that's paint, basically, and it'll be peeling inside six months. The weave on top matters too, a tighter low pile holds its shape and won't bunch at the edges, which is usually where the slipping actually starts, not in the middle.
Measuring for these is less forgiving than for a regular rug, because grip only works if the rug is actually sized to the space it's trying to hold its ground in. In a hallway you want it snug enough that both long edges meet resistance, a wall or a skirting board, rather than floating in open floor where it can creep sideways over weeks. In front of a sink or stove, go for something that covers the full width you stand in, not a narrow strip that leaves one foot still on cold tile. The common mistake is buying to match a photo of a kitchen three times the size of yours, and ending up with a rug that curls at both ends because it's too long for the run.
These earn their place in kitchens, bathrooms, entryways, anywhere wet feet or hurried feet cross hard flooring. They're also the right call for older folks or small kids in the house, where a sliding mat is a genuinely dangerous thing and not just an annoyance. In a formal living room or over thick carpet they're wasted, the grip has nothing to bite into and you're carrying the cost of the backing for no benefit.
Where they fall short is heat and hard use together. Leave one under a sunny window for a summer and some backings go brittle and start to crack at the folds, so check care labels if the spot gets direct sun for hours. They're also not a long term fix for a seriously uneven or warped floor, no amount of grip beats a dip in the boards.
Next to one of these I'd put a decent floor mat at the actual threshold, so you're wiping feet before they ever reach the part doing the real work.