What have you seen them used for?
I used GUIDs as object identifiers in large e-commerce systems, where multiple instances of the server application create them.
In a situation like ours, where after the creation of the the id nobody cares about whether the string is a GUID, I am not too fond of them - they are hard to read, remember, or compare (depending on the context/algorithm for generation, you may have to check each character) and take up a lot of space as a string (16 bytes of information in 36 characters).
Of course it’s a viable fallback solution that will always work, and you get it for free. Between this and “manual” id creation we use (“Player”), I guess we could insert a type of id construction that tells you what the string stands for, e.g., for enemies, concatenate scene name, unique name and enemy type or number within type (insert separators as needed). But I have not finished the course series yet - maybe something like that is introduced later.