[hbien]

It could be a pro or a con, it's dependent on the company culture.

I worked at a company with unlimited vacation days where management "trusted" you to make the right decision on how much rest you need. This is good in a culture that encourages rest. It's bad in a company that measures productivity by time spent at your desk.

Having untracked vacation days as a benefit, I definitely prefer a known hard limit, but that's my personal preference.