I had IPSec VPN set up on my iPhone for a year, zero problems. Native Apple client, no apps to install, just a profile file. It is always on for all traffic.
The client side story for IPSec is great, but configuring the (strongSwan) server is far from trivial. There are many decisions to make, and mistakes to avoid.
Yes, amazing projects like Algo exists, but you can't use these on all platforms (ex: OpenWRT).
My hope is that wireguard will provide a much easier (and safer) setup experience.