Ekman has a very long trail in the scientific community, and any academic who is worth their salt will know him since he was the responsible in providing empirical evidence that proved the universality of emotions and facial expressions. Before Ekman anthropologists thought that facial expressions were culturally-dependent. Ekman proved that facial expressions are universal.
Wow just browsing through some of his published journal articles seems he is FAR more known for his work on universals than for lying in general.
As far as I understand, that work is legit. His lie detection, however doesn't seem to be.