The biggest plus is protection against SIM hijacking, which I agree is a big plus, but no one should be using SMS for 2FA anyway.
Like many companies, if you keep calling you'll eventually get someone awesome who can pull strings. But it's frustrating.
I've had the experience twice of phones getting lost on the way to me. They would insist on running an "investigation" that could last weeks or never resolve, before they would send a new device. In both cases, I had to be pretty pushy with the agent that the phone either fell off the truck or someone at FedEx stole it. Usually I needed a new phone ASAP due to a failure.
Don't get me wrong, Fi is awesome, especially for international travel. Just show up at the airport and you've got service. The data rate structure is totally fair for how I use it. But there are definitely benefits to having a local Apple Store or Best Buy with a compatible phone in stock.
This outage is a bit worrying though. I'm sitting here waiting for a very important call and now found out, by reading HN, that they may not be able to reach me.