I'd never heard of them before, but once she explained, I decided that it was such a lovely personalised thing to give or make for your child.
They're basically a cloth book with around 8-10 cloth pages dedicated to different skills - counting, colour identification, hand-eye co-ordination (zipper on tent and laces on shoe to fishing magnetic felt fish)
If you're into craft you can make one, there are plenty of ideas, instructions and templates for free on the internet.
Have a squizz at some of these to give you an idea about them.
You can use them as a wind down tool before sleep, or on long car journeys, plane trips etc.
You could make a personalised family cloth book to help your child transition on the car journey from childcare to home. How many toddlers out there have a tantrum when they have to go in the car seat?
A quiet book could distract and make your journey home so much more pleasant.
If you're time poor, like most of us then buy one. Amanda did say it was time consuming.
Here's a few sites where you can buy them.
Etsy are good for handmade things.
They vary in price from $10 to $206 for a personalised handmade book.
this one gives you a pdf of the pattern (not the book, just the pattern).
So take your pick - make, buy the template or buy. It doesn't really matter. I think they're a great idea and may buy you - the parent- a bit of quiet too!