I see this as priced against monitoring services and systems that phone them.
Compared to those, this is cheap.
Then if you have high-ceilings it makes it much more difficult (have to go get a ladder in the middle of the night).
It will freak kids out, they're not fun to get back to bed.
The elderly or disabled might not be able to remove the battery or remove the alarm.
I'd say it's definitely a step in the right direction and in-line with Nests other product (probably much of the same hardware).
What's next for Nest? Lighting? Door locks? Security system?
Put in a lithium battery. The lithium battery will last for the entire 10-year life of the smoke alarm. Thus, you should only replace smoke alarms -- not the battery.
In fact, these days, they're selling smoke alarms with sealed non-replaceable lithium batteries. This prevents people from attempting to use an alarm past end-of-life, and thus getting a false sense of security.
The problem with a nanny state is eventually people rebel. The future of smoke detection is high profits for mfgrs and residents will spend an hour their first day in new premises disabling and disconnecting the devices. The overall effect on safety will be a profound net decrease, although theoretically on paper we'll never be safer.
Haven't given me any problems. Haven't heard about them giving anyone else any problems. You seem to be dismissing something that already has a proven track record. Why is that?