I don’t get it. For similar $ or not much more can’t a full function cheapo tablet (or an older, past its CPU prime tablet) do the same thing and much, much more?
“Battery back up”? I didn’t see any power cord in the ad, but does this clock require 110V to operate? Deal breaker for me, if so.
Yes, it plugs into a wall outlet based on answers in the Q&A on Amazon.
does it auto dim, for the night?
Bought an oversize digital day/date clock for elderly parents (no smart functions like reminders but it did have an atomic clock). Great decision. Though I can’t speak to this specific item, it’s a highly recommended solution for folks that are hard of seeing or have mild cognitive issues. And much better than a large LED clock which can be annoyingly bright at night and also have harder to read digital style numbers.
Clocks powered by AC will almost always stay within 10 seconds of correct time. The electric utilities make sure that the frequency on the AC lines averages to almost exactly 60 Hz over a 24-hour period. A clock with its own oscillator as a reference will drift over time unless it compares its time against a radio signal (WWVB or GPS) or an NTP server on the Internet. An accurate oscillator costs money and isn’t usually included in a consumer-grade device.
AC clocks stay accurate if they count the cycles, but this is a DC powered clock. It is rated at ± 10 seconds/day. After a week it could be a minute off. It will likely need periodic resetting.
So for only $43, I can finally know what day of the week it is again??? 
Where I would have put the clock I have no electric outlet—AC accuracy does me no good whatsoever.
Indeed, I have a really dumb clock that was programmed for the time; I cannot change the time on it other than to change the time zone/daylight savings settings. It’s several years old and has drifted to 20 minutes ahead of time. Dumbest damned alarm clock I’ve ever owned.