I have worn shoes like that for a pageant and dances but never had the need for a cosplay.
However, they are easy once you get the hang of them but you really need to be careful with balance.
I have also tried on those exact shoes if not ones very similar while in a halloween shop. They have great support with the strap but could easily twist or break your ankle if you fall hard enough. (But that is with any shoe, really.)
I would practice with the shoes themselves before covering them with the fabric.
Another thing you might want to do is invest in those ankle stocking things. Depending on your feet, how you walk, and how long you wear the shoes, your feet can get cut by the plastic by your toes. The stockings will protect your feet better. Since the shoes will be covered you would also just wear normal socks but they might be too thick.
Another method to decrease the chance of hurting your feet is to wear the shoes around the house and stretch out the plastic a bit.