With the app it's very useful to be able to find out the location of the car, the status of the doors and windows, the current mileage, and be able to control the climate (Dog Mode, etc), warm up on cold mornings, cool down in summer. You can also get important notifications (i.e. Climate mode on for a long time, Door/Window is open, etc )
You might knock the remote climate feature but if you have dogs/kids/elderly it really improves their quality of life.
There's another recent feature which supports streaming music such as Apple Music, without your phone needed. This is convenient and useful.
Tesla charges $9.99 USD a month for this which I find to be extremely reasonable. ( I am an SRE and I know what it takes to maintain scalable secure infrastructures )