Nest Protect is different in that it also provides spoken alerts, which not only tell you the nature of the emergency smoke or carbon monoxide, but also the room in which it's occurring. The Nest Protect runs self checks to ensure that everything is working as it should; while this includes turning on its siren once a month, it's a welcome feature. The app gives you advance warning, which is also nice. The Nest Protect was the only smoke detector to pass all of our tests. Through the Nest app, you can monitor the status of the detector, as well as any other Nest products you have, such as the Nest Cam and the Nest Learning Thermostat. The app gives detailed information on when the Nest Protect last checked itself, and if there are any issues. From here, you can also silence the alarm if it goes off accidentally while you're cooking a steak, for example. MORE: Smart Home Guide: What to Know Before You BuyAdditionally, you can link the Nest Protect to other smart home systems, such as Google Home and the Mini and Max, TP Link smart plugs and Philips Hue lights. Bottom LineAt $100, the Nest Protect is one of the most expensive, but also one of the most comprehensive, of the smart smoke detectors we've tested. Not only does it pick up several types of fires, as well as carbon monoxide, but it also does the best job at alerting you of the danger. And, it works with a wide range of smart home products.