Unlimited Vacation Time Pros and Cons

Unlimited Vacation Time Pros and Cons Compilation 2018
I was wondering if anyone actually has experience with "unlimited vacation". When I first heard of it on this list, I thought it was too good to be true, and I was right, at least according to this article I read:
I am wondering on average how many vacations people actually end up taking. Anyone dared to take more than 4 weeks (real ones, not work-vacations) and not fear retributions.
I worked in multiple companies that has such policy. The actual vacation length and frequecy culture varied from company to company and was just not clearly stated, one had to kind ask around to see what's appropriate. It varied from 2 weeks in a row being a very long vacation to 3 weeks + 2 weeks later in the year of being totally fine + some single days here and there.
Our company went from unlimited vacation to 20 days annually, partially because there was the perception that the policy was being violated, or at the very least being taken advantage of disproportionately. We're a relatively small team so it felt like fairness was paramount to avoiding intra-office mutiny :) 
I think the size of the team matters a lot, as well as cultural expectations (of course). We're part of an international company so in a sense it felt fair to mimic the parent company's vacation policy, but that doesn't really work in practice. 
I much prefer mandatory office closures for certain periods. My last employer had an office closure the week between Christmas and New Year's, and the thing I liked most about it is that people tended to actually travel during that time, and it felt very much like school when they returned because everyone would share stories from their time off. 
Thanks, everyone, for your thoughts. What I am still unclear about is how this unlimited vacation policy is beneficial to the employee? It is sold as something cool but so far I haven't heard that it adds value compared to the traditional way of stating plain and simple what the vacation days are. So when I am considering joining a company, I have not seen reasons to believe that as a selling point, but rather, just yet another thing to have to deal with within a company culture I don't know yet.
I must be missing something here
I like set vacation policies better, in theory . Devil is in the details. I just switched firms and my former firm cut me a check for the two weeks I hadn’t used. That meant I didn’t have a pay gap for the time I took between jobs. Very generous of them and since i’m a lawyer in a firm it wasn’t necessary since I wasn’t working at full  capacity so I felt strange taking the accrued time (but didn’t complain). I’m in an area that gives 4 weeks of vacation and assumes we are working hard when not away. If I only got a week or two then I might prefer a more “honor” system type of vacation policy. And I wouldn’t abuse it. I don’t take 4 weeks off. I take about 2
I'm currently interviewing and a few places mentioned their unlimited policy as a selling point. I would prefer a specific amount of days as well because you can get paid out when you leave. 
I generally take at least 4 weeks throughout the year because that's what I've had so far at all my jobs and most of that is to visit family overseas. 
If we got to the offer stage do you think this is something to bring up to let them know ahead of time? Since I won't know the culture and I don't want them to think I'm taking advantage once I accept. 
My experience with unlimited vacation is:
1. I am on the work-life team of our organization. Research shows that overall people do not take advantage of the policy and in fact overall people take LESS time then if there was a set policy. People NEED vacation to recharge and be productive but there is anxiety around what is the right amount of vacation to take? Most people err on the side of caution and take less in order to fit in with the culture.
2. My husband's company had unlimited vacation. Most people were taking 2 weeks or none. Some of the high powered workahaulics in the org of course are in senior management and they were not taking vacation. Employees took their cue from them and were not utilizing vacation. Now they have 4 weeks PTO and everyone uses it. 
And just an FYI, many orgs KNOW that people will not use unlimited vacation but that it sounds great on paper to millennials for recruitment. 
I have 4 weeks paid and 1 week personal and the week off between Christmas and New Year's and I use every minute of my vacation and am a really productive employee  
I’ve read analysis that agrees with the feedback above. Typically flexible vacation policies look good on paper but are less favorable for employees and save the employer money.
We went from a policy of x number of days per year to unlimited. From a corporate perspective it was good because holding millions of dollars in cash is difficult. From an individual perspective (I looked at my days off) and I'm just at 4 weeks from before and after. I also happen to have taken two paternal leave, which for me was 8 weeks each. I had less time off before the policy, for reference.
It comes to how you manage the unlimited policy. I work for StreetEasy, part of Zillow Group, and I encourage people to take time off. Am appropriate work-life balance is encouraged.
I can't say that I've observed much of a difference, though I've seen that some are able to take 5 weeks now without much issue.
I think it depends on the culture of the organization - at my company, people do indeed take 4 weeks or more of vacation. On top of the actual days off, this policy has affected the culture in that people feel comfortable working from home a lot. Now, when I consider other opportunities, if they offer 3 weeks of vacation, I feel very restricted. 
As for how an employer benefits, they do not have to pay for any days not taken and given that empirically, people do not take a ton of time off, that means they're saving money. 
I second these comments (although I worked at the same company as her!). When I started there, I thought the unlimited PTO policy must be too good to be true, but in reality it turned out to be everything I would have hoped. It definitely varied by team but I'd say I took over 4 weeks every year, and one year was 6 weeks. They had a caveat that anything over 30 days in a calendar year was supposed to be approved by your manager's manager.
I'm sure it varied by team, but with a supportive and flexible manager (and after proving your value and working hard!) it was taken seriously and I never sensed any judgment. For a while I wouldn't even consider interviewing anywhere else that didn't have the same policy. At my new job, I have 3 weeks a year and the only way that works for me is with a very flexible culture around working remotely. 
I hope to see more companies move in this direction!