But that's the whole point of Google Fi. They partnered with Sprint and T-Mobile.

When your in Alameda and Sprint sucks, Google puts you on T-Mobile's network, and you get better data + coverage.

When you head to the rural Midwest, and T-Mobile has EDGE or no service at all, Google can put you back on Sprint LTE and it's at least better than EDGE on T-Mobile.

If this works the way they describe, then you win in both situations -- you get the best of either network, wherever you happen to be.