I've used it and can heartily recommend it. Don't bother with making a bed of sand. It doesn't make "bricks" that you place anywhere. It just lets you pour in place. Just dig out the sod and compact the soil, and you're ready to go.
You can form circular or curved pathways using the methods Johnny quoted above. I prefer the first method, too. Just use Willian Alexander's "Wet on Wet" technique (
), and you'll be making curved pathways in no time.
This thing is handy, but don't kid yourself. Mixing and forming concrete one bag at a time is hard work.
For an extra bit of finish, you can get powdered concrete stain and sprinkle and float (using a floating tool) it on top of the concrete before it sets. It makes it look more stone-like and comes in different colors.