An "I love you" will is a simplified last will and testament that leaves everything the testator owns that can pass via a probate estate to the surviving spouse. Despite its name, an "I love you" will might not be the best estate planning tool to show love to a spouse.
Does not plan for the possibility of the surviving spouse's disability or developing special needs. For example, it provides no management, as a trust does, in case the spouse becomes disabled or incapacitated.
Doesn't consider children, grandchildren, or other loved ones, which are crucially important considerations for second and later marriages.
Provides no Medicaid (or VA) benefits since all of the assets that the surviving spouse receives are countable for Medicaid and VA purposes.
Does not control or consider testamentary substitutes, such as life insurance policies, bank accounts, or retirement accounts with completed beneficiary designations. Testamentary substitutes sometimes hold the most value in a decedent's estate.
While an "I love you" will is appealing because of its simplicity, depending on the married couple's facts, a trust (revocable or irrevocable) might be a better estate planning tool. Also, as Lacey suggests, a good estate plan is a comprehensive one that considers both probate and non-probate assets.