Not had it for very long, and thankfully not had to use it in anger yet but very impressed so far. Good build quality.
This alarm provides good general protection. For extra protection, Kidde does recommend photoelectric smoke detectors as well (as they detect slower, smouldering fires more effectively).
There are 2 different siren tones depending on what is detected, but you don't have to remember which is which as it also has a voice prompt that clearly states which has been detected. The sirens are very loud and piercing but the voice alarms could be a little hard to make out if you're not in the same room as the alarm (though presumably it wouldn't matter that much). There is also a voice prompt that warns when the battery is low.
The design of the backplate ensures that batteries must be correctly fitted or else it won't install.
Only drawback is that it takes 3 AA batteries, which is a bit irregular but not that much of a con.
Very pleased so far!