What are disadvantages of promissory notes?

Promissory notes can have several disadvantages, including the potential for legal complexities if the borrower defaults, as enforcing the note may require costly legal action. They typically lack the formalities of a secured loan, making them riskier for lenders if the borrower fails to repay. Additionally, they may not provide a clear means of recourse in cases of disputes, and their terms can sometimes be vague, leading to misunderstandings between parties.