I like the Aqara G400 because it nails the stuff you actually feel day-to-day: a slimmer design, PoE, and a vertical 3:4 view that fills my phone screen. Just don’t buy it assuming it replaces the G410 as a hub—it doesn’t, and that changes what you can do with other Aqara devices.
Pros
+Vertical 3:4 aspect ratio fills the phone screen better
+Power over Ethernet support
+Slimmer, more appealing form factor
+Better weatherproof rating than I expected
Cons
-Not a hub device (can’t replace G410’s hub role)
-No battery option
-Slightly narrower field of view than G410
-MicroSD card is in the doorbell, so it’s harder to access
-Loses millimeter wave in favor of camera-based motion detection