A valid will must be in writing and everyone over 18 should make a will, DIY wills are possible if the position is straight forward, but most people in the legal profession will confirm that they are able to earn a good deal of money out of unclear DIY wills. Some common mistakes are:
Not being aware of the requirements to make a will valid.
Beneficiaries who also witness the will.
Taking into account that a beneficiary may predecease the person making the will.
The effects of marriage and divorce.
Unwitnessed changes to a will.
both my parents made out wills, father left all to mum, mum left all to kids, mum died first, luckily error spotted before either departed. So to answer the question a verbal will is not valid.