I own this model, and have installed it for others.
This is the 1st Gen, which is identical to the latest gen in all but 2 ways: no Apple Homekit support, and a very slightly redesigned battery cover.
At the time of this posting, it is supported by Amazon Alexa, Google Home, IFTTT, Nest, Wink, Harmony, Honeywell & Xfinity Home. No Samsung SmartThings support.
As with all smart locks, it will still function as a normal mechanical lock if it loses power.
This replaces the interior portion or your existing deadbolt lock, so your physical keys will still work. That also means that you must have an existing lock. This does not come with a deadbolt, tumbler, or exterior lock face.
For me, install has never taken more than 10 minutes.
It runs on 4 AA batteries, which last about 9 months. The app notifies you as the batteries start to run low.
Because it runs on batteries, it can’t produce much torque. If your deadbolt has a lot of tension on it (like from thick weather stripping), August will not be able to overcome that when locking the door. In my personal experience, it can produce enough torque to unlock a deadbolt under tension.
This uses Bluetooth Low Energy (BLE), not wifi, so you cannot unlock/lock this remotely without buying a separate add-on (August Connect, which you can usually find on Amazon for $50 - $60 used/open-box).