Unlimited Holidays

There was a prior discussion about this 2 or 3 years ago when a few companies first started a policy of allowing unlimited holiday.  I am interested whether anyone has experience of how that has worked out.  The last discussion, set out all the possible pros and cons of establishing a policy like that but has anyone on this forum had actual practical experience of it in their company?

There are increasing numbers of US companies doing this - including my own - with some success.  However, the UK law and culture is very different and there are practical and legal issues that would need to be addressed here.  However, this is a potentially differentiating benefit.

Anyone cracked that?