Ability to execute on the solution. Does the team have the passion, technical & business skills required.
does the problem exist & does the solution solve that problem.
Is the solution innovative or novel & have a strong value proposition.
Do you have an indication of product-market-fit, are there paying customers. Do you have a solution in the market.
Are you targeting a sizeable market & how will the solution be scaled to service it.
Is the solution a good fit for the angel and his or her personal background.