Probate is the legal process in which the court and lawyers will take over control of your estate and affairs should you die with or without a Will. It is time consuming. The average probate can easily last 1-2 years, or more. Your surviving spouse and children will be at the mercy of the court and will have to ask for mere living expenses. It's humiliating and very stressful.
Probate is very expensive.
You will lose all privacy during probate because it is a matter of public record. Anyone and everyone will know exactly what you owned and who you gave it to. Your private affairs become everyone's business. Joint tenant ownership does not eliminate probate and its financial and emotional expense. By holding your assets as joint tenants, you are throwing away a very powerful tax advantage called Full Stepped Up Valuation.