My kids like them, they used to bury themselves in blankets and kick them to the floor in their sleep. They say this feels like a hug. The elastic is firm but not tight which they seem to prefer. I've noticed they settle faster & don't overheat or end up cold overnight. They say they are sleeping better. Work well with weighted blankets also if people like the pressure.
I went and got some bigger ones for myself & now I prefer them too. If you try one and like it get a few sets & consider a range of different fabrics etc. People who like them tend to pull them over themselves and 'snuggle into them'. No signs of stretching or sagging yet but they will likely get good use. Also helps to have a good quality & very clean mattress because they fit around the entire mattress. If your kid's is a little dated or soiled use TWO mattress protectors, first fit one to the underside of the mattress, then fit the second on the topside as usual so the whole mattress is enclosed in a clean layer. Wash inside out to prevent fluff etc from under the mattress transferring inside the sheet when washed. Fitted sheets still work fine.
