Results with animal Eye AF were excellent—see Boots the Cat with Eye AF.
In part, this page looks at the effectiveness of Eye AF on the Panasonic S1R for human eyes—not quite good enough, which is a pity given the gorgeous lens performance.
In spite of the failure of Eye AF to nail focus on the iris of the eyes, these examples nonetheless show off the spectacular rendering of the Leica 50mm f/1.4 Summilux-SL ASPH for portrait applications.
In diglloyd L-Mount Mirrorless:
Leica 50mm f/1.4 Summilux-SL ASPH Examples: Portraits using Eye AF (Panasonic S1R, Eye AF)
Includes images up to full sensor resolution.
f1.4 @ 1/200 sec, ISO 200; 2019-04-29 19:41:29[low-res image for bot]
Panasonic S1R + Leica 50mm f/1.4 Summilux-SL ASPH
RAW: Enhance Details, LACA corrected, distortion corrected