for me biggest problem was the panic when I send bitcoins and there is no way to get them back and you are not sure if the other person received them it is all very nerve wracking actually.
if you mean panic when you send bitcoin to wrong address because bitcoin are irreversible then yes it was problem for several newbies, that's why people must know the power of irreversible transactions , they need to double check everything is okay to go to avoid something like sending wrong aount or wrong address.
