There's nothing inherently flawed about the thermostat, combo smoke/carbon-monoxide detector, and other individual pieces in this new lineup, but First Alert missed a great opportunity to create a compelling smart-home safety system.
Each device can send messages to your smartphone, for example, but none of the devices talk to each other. They don't even send alerts to the smartwatch. To top it off, the apps aren't integrated--each one operates on a completely stand-alone basis. At least they have a similar look and feel.
I'll start with the smart watch: You'll find all the usual features here: An OLED display, Bluetooth connectivity, heart-rate and sleep monitors, and so on. The one innovation is the ability to trigger your phone to call 911. If there's an emergency, two taps on the face of the watch will trigger your Bluetooth-connected phone to dial 911.
What's missing None of the other components in the Onelink series communicate with the watch, and you can't use the watch to interact with any of them. You can't tap the watch to bring up the Wi-Fi thermostat's UI to adjust the temperature. The smoke/carbon monoxide (CO) detector, Wi-Fi environment monitor, and safe don't send alerts to the watch informing you that something is amiss. The monitoring devices don't trigger the Wi-Fi security camera to record a clip to capture the fire as it begins to smolder.
The tabletop Wi-Fi environment monitor is able to detect lower levels of carbon-monoxide than the smoke/carbon monoxide detector, but it can't trigger the voice or siren in the ceiling-mounted device to alert you to the emergency. All it can do is light up its own LED and send a message to your smartphone. The environment monitor can also measure the room's ambient temperature and humidity, but it can't relay a message to the Wi-Fi thermostat to have your HVAC system adjust the temperature or turn on its fan to get some of that humid air moving.
The smoke/CO detector, meanwhile, can talk to alert you to an emergency (a First Alert spokesperson told me that sleeping children awaken more quickly to voices than they do sirens) and send messages to your phone, but it can't tell the thermostat to shut off the HVAC system so its fan doesn't circulate smoke from the room where the fire started into the rest of the house.
On the upside, the batteries in the smoke/CO detector last up to 10 years, and the voice alert will let you know when they're close to failing (and it won't be in the middle of the night). When the batteries fail, you replace the entire device. First Alert also offers AC-powered versions (with battery back-up) if your home has that feature.
If you're still interested, the smart watch ($200), smoke/CO detector ($110 for the battery-powered model, $120 for the AC powered), and Wi-Fi thermostat ($230) are available for pre-order on Amazon now. The safe, environment monitor, and other devices will be available later this year, but First Alert did not provide pricing information for them.