The obvious first, it is expensive. It is much more expensive than all the detectors I have used.
However, it is also the best by far. It detects smoke and carbon monoxide simultaneously, it is wifi-enabled, easy to install, the batteries last a long time as long as you use the energizer ultimate lithium aa (l91) ones. If you use others, it will consume them very quickly.
Additionally, it has motion and light sensors so that at night, if you pass by it, it lights up to help you see ahead.
The only curiosity is that Google still hasn't integrated it into Google Home and requires the Nest app. A minor inconvenience, but it is strange.
Its lifespan is 10 years, after that you have to throw it away (like all detectors).
I will buy it again to cover the rest of the house.
I recommend it without a second thought.