Not an expert in this, but you would need a lot of eigenfaces to capture the variance (i.e. a lot of upfront cost storing all the eigenimages). It might be good

Not an expert in this, but you would need a lot of eigenfaces to capture the variance (i.e. a lot of upfront cost storing all the eigenimages). It might be good for something that is very standardized (e.g passport photos where everyone is in the same position) but otherwise I think there probably is too much variance to keep the number of eigenimages to a reasonable number.