We've tried it, it's OK but it's not good for coverage. It's less coverage than tempera paint. Really just for kids not to ingest or make a mess with. Also, make sure you get food coloring GELS (this is Jilly's advice here, she's sitting next to me) Wilton or Americolors because the liquid stuff won't be this vibrant. It's also really hard to get out of your hair if it dries.
But if you want a safe alternative to paint, or you're out of paint, it'll work in a pinch. Thanks for sharing!
I've had bad luck with food coloring staining my skin and clothes. It sounds like a nice option for kids paint but with all that flour in the recipe it seems like it would be very hard to get our of hair too.