It's great if you feel you can actually take it, but most people don't.
It generally means there isn't a defined amount or minimum amount, and everyone knows if you actually take a lot of time off, your output will not look as good compared with your colleages.
The undertone of competing with colleages for recognition hasn't gone away after all. Even if you're not ambitious, you probably value job security, so you don't want to look like a slacker or low output person.
So in practice, at "unlimited vacation" companies people tend to take less vacation than they do at companies with a defined amount of vacation.
Local culture also ends up influencing what people do. I'm working for a company that has "unlimited vacation" and also a very international, fully remote workforce. What they have found is, even though the company policy is the same everywhere, people in the USA choose to take much less official vacation (up to about 2 weeks) than people in France (about 5 weeks). This is the individual's choice remember. Also the amount people have taken has reduced during the pandemic.
They are actually trying to get people to take more vacation, and have set a minimum amount to try to enforce this. My guess is people don't want to be seen as slacking during a time when alternative employment prospects are uncertain and keeping remote work is a priority.