I think the FACS is a pretty clever project. It's mostly accurate and was made with real studies and facts from human facial expression. I think the FACS is a very intresting concept but I do not place it as valuable.

For one, the FACS can't be accurate all the time. Humans are complicated and it's often very hard to tell how they're feeling. Most people like to "fake" their emotions. They're smiling but they're actually feeling awkwardly uncomfterble or angrly calm. It can be easy to trick the system, many can fake a genuine smile and confuse the system into thinking wrong.

Another reason is that the FACS doesn't provide any real benefits to anyone. Sure it can be a little fun to test out different emotions to see different ratings but it dosen't actually provide any information that can be very useful later on in life. People have different faces for different emotions, none are the exact same. Similar yes, but it varies and mistaking an emotion for something else may bother said person.

In conclusion, the FACS can be accurate but holds no value to society. It can be good fun, goofing around with freinds when boredum hits you but it's nothing else. It's a one time game that'll get boring quickly and thrown away for the next big project.