Toms are definitely adorable on everyone's feet, super comfy to wear around town, and look cute with any outfit. But I don't recommend them for WDW. Not only are the souls flat (someone mentioned needing cushion from the impact of just walking) but they can also get wet from the many puddles around WDW and the typical Floriday freak rainstorm in the middle of the day. Also, after a couple of wears in the sun - they can get smelly...
They would be cute to wear at the hotel if you need something simple to slip on for a trip to the refillable mug station or to walk around and explore the resort, but bring sneakers to wear to the parks.