Why terrible? Your own wifi would still work inside the cage, would it not? As would your Internet uplink over cable/fiber/DSL/whatever. The only downside would seem to be cell phone service, but you could just use VoIP and Wifi for that while inside the house.

The real downside of course would be the cost. Shit, maybe I'll need to get a real job again after all...

I'd like for just one of these people offering the "solution" of turning our homes into faraday cages to show us that they've actually done this with their homes.

I would do it. I get cell service over WiFi. It has absolutely no downsides for me.