Unlimited Vacation is the same as saying Unlimited Salary, its total BS. Without set guidelines in your employment contract of what PTO you get in exchange for working there it creates a drawn out negotiation between you, your manager and your team of how much vacation you actually get.

Its just better to know for sure what PTO you are entitled to in your employment contract. Would you accept a job without knowing what the salary was? Keep in mind that vacation days are something that you are EARNING in exchange for your work.