I've been playing with this, and it's mostly good. It solves the key forwarding problem in nested Linux VMs (-A forwarding is kind of bad).
I do find it a bit silly that they don't support any iOS or android ssh clients, so they only way to authenticate ssh from an iphone is to connect to a VM first where the linux client is installed.
Yes, AgentForwarding is a bad idea... but thanks to ProxyCommand (and now the simpler) ProxyJump, I haven't needed to use it in years.
It is neat, but only for SSH. Plus, they're a new company I never heard of. Why would I trust them with my SSH keys?
Iirc their clients are all opensource, go audit the source code and build your own binaries.