First off, it's worth buying these (or similar) products just because you don't have to manually walk around turning a room full of lights on and off every day. However, I bought them about 7 months ago and they worked great and were easy to set up, they still work great but over time the signal gets weaker for them. It could be that the battery is dead, but it's still a bit early for that. I used to be able to point them anywhere and control any light, but now the sensor really needs to be in line of sight of the lights. They still work above 10ft so can't complain too much. I'll update this if it turns out to be the battery.
Lamp LED Xiaomi Mi Smart LED Bulb Warm White (XMBGDP01YLK), E27, 8 W, 2700 K
26 Review
Smart bulb Yandex with Alice, base E27, 8 W, RGB color
76 Review
Ceiling lamp Yeelight YLXD013-B, 50 W, number of lamps: 1 pcs., color: white
62 Review
Lamp LED Xiaomi Mi Smart LED Bulb Essential (MJDPL01YL), E27, 9 W, 6500 K
113 Review