Just a data point: my Jaguar Remote Start app on my iPhone works brilliantly and I use it every day these days. I work in NY and commute to the city from the burbs; given the freezing cold around NY these days, I start the car when my train is 15-20mn away from my station. By the time I get to my car, the interior and the engine are warm!

 

Winters temperature in NW England, (UK)
probably not as cold as NY, nevertheless I find the Jaguar remote app very useful and use remote start when temperatures are near 0°C to warm engine and car interior before I get in.
I use the Android version (Note 9), also use automatic journey tracking to help manage travel expenses.

 

I used the remote app to lock the car when I was at Bass Lake and my 17 year old was at home alone. Brilliant!