While the policy is ripe for abuse and I suspect there are some limits there (more severe punishments for missing project deadlines or leaving work unfinished). THat said, I think it's a fantastic idea. Especially as someone who works for a fledgling company whose employees are all over the world, I'm already able to take time off as and when I need it. We're measured on our work completed and contribution to the project, not how many hours we've been sitting at the computer. If we're slacking off and not pushing any improvements or making any headway, words are had and punishments for taking liberties can be as severe as being sacked, which has happened. It's a modern holiday policy for a modern working world and I think will be rapidly adopted by other forward-thinking companies, big and small, sooner that you'd think.
Have flown once with Virgin Atlantic and never again - they were the laziest cabin crew we have ever had the misfortune to encounter - clearly they had already started to follow this new policy of taking time off whenever they liked, as they did the absolute minimum on our flight!
Before retiring in April, I had my last contract at Adobe Sytems in San Jose, California. Adobe has a similar holiday policy which is not abused by employees. In an environment where people work from anywhere at any time, allowing employees and managers to agree to time off makes sense.