I'm the weirdo that actually loves this. I always feel compelled to hoard limited resources, including vacation hours. I'd estimate that I take 100%-200% more time off when I have "unlimited" PTO. When I'm working against a bank of hours, I tend to never use the full amount, just in case I might need it. With unlimited PTO, I'm much more likely to take random days off that I need, in addition to the week or two here and there for family vacations.