Like the pitch for the product mentions, people who spend long stretches of time sitting at their computer come up with all sorts of ways to position their feet to be comfortable. We use boxes and footstools. We put one leg then the other up on the seat underneath us or sit cross-legged if we're agile enough. (No offense, but most engineers/gamers are not agile enough).
When you're height challenged as well as bifocal challenged like myself, there's the added conundrum of having the seat low enough where my feet might barely reach the floor, leaving my bifocals in the wrong position to properly read the screen such that I have to work with my head tilted backward or zoom in and make my font so large my screen looks like one of those Reader's Digest Condensed Books in Large Print. Or, I can raise my seat up to where my bifocals have a fighting chance at helping me read the screen and then my feet dangle a foot off the ground and I fidget and wiggle trying to get into a comfortable position, but invariably my feet fall asleep. So when I get up to go to the bathroom or get a drink, I stumble and can't walk.
I didn't go for the fleece or heated models. I went with the basic mesh version in purple as you can see from the foot selfie I took. I already have a heater under my desk that warms me as well as my feet so I can't review those models.
I use my foot hammock every day and I love it! It has solved all my desk-sitting, heigh-challenged, bifocal-challenged, sleepy feet problems. Get one of your own. You can't have mine!