I bought the brown ones in a size 5 for my one-year old who has been walking for three months.  These are very sturdy, but just enough flex for him.  They would be too stiff for a baby just learning to walk.  The only thing I don't love is that they chaff his foot at the ankle strap a little.  Not enough to  take them back, but enough that I probably would not leave them on him all day if he was walking everywhere so for older kids, you might want to be aware of the potential there.