I preordered my lock and have had it installed since they were introduced. I love not having to get my keys out as well as allowing the kids to get in with the key fob. The only negative is when it may take 2 or 3 taps to lock or unlock. This is a software problem with the phone as restarting the app (that I never turn off) fixes the problem. The last app update improved the speed greatly.
In regards to installation and serviceability: it installs just like any other deadbolt, very easy. And sure enough when the batteries die you not only get a notification on your phone but the light ring warns you every time you use it for a couple of days prior so you really can't get caught with dead batteries and no keys...