While the default smart mode does seem to marginally improve battery life, I noticed that it prevented many of my apps from sending notifications. (androidauthority.com)
So if you're doing a walk - through video or want to keep the drone close - by smart mode is great. (techwelike.com)
Smart mode allows you to easily focus by tapping on the screen, but as that that focal point moves away from the center, the images start to get more and more fuzzy. (androidauthority.com)