Most people don't appreciate how long a Google Fiber roll-out takes. I waited nine months to be connected and I was lucky. My parents had to wait two years. Google offered very little visibility into when the install would take place. (We've been waiting two years now for a hookup at my small business, with no end in sight and no way to get an estimate from Google.)
These realities gave Comcast a giant head start to perform customer retention jujitsu. It basically took a steely determination (or an implacable hatred of Comcast) to resist the deals being offered in all the calls, letters, and emails. You could accept their deal -- and be enjoying 12x faster internet within a week -- or hold out for Google Fiber at some undetermined future point.
So many folks were taking the bait that Comcast brought a great many contractors in from out of state to handle the volume of upgrade service calls. For months, nearly every room at a Residence Inn near my home was occupied by out-of-town Comcast crews. Every space in the parking lot was filled with a Comcast van at night (hilariously, each van had its orange cone deployed in front as per company requirements).
When I finally was able to contact Comcast to cancel after our Google installation, the rep had a special script for Provo customers. It centered around questions of whether we were actually achieving gigabit speeds in real-world situations. Though I still proceeded to cancel their service, it was a pretty devastating critique as no one connecting over wifi (which was almost everyone) could even achieve the 250 Mbps speeds Comcast was offering, to say nothing of the gigabit speeds Google had sold you.
I'm happy with Google Fiber overall and I certainly don't miss Comcast, but they wound up being a more capable competitor than I'd ever have suspected possible.
That doesn't prove anything, but their prices certainly are eerily competitive with Google's in any market that Google entered, while they're... terrible everywhere else.
We signed up for Time Warner and the rep expressed surprise that we wanted them just for Internet, since Google Fiber is a thing, until we explained the situation. That should give you some idea of how it affected them.
Prices have dropped for other providers, and speeds have gone up, though they're still worse than Google Fiber. It's been great. I'm really bummed that this may mean they won't ever hook our street up, or at least that it'll be delayed until someone else takes over their infrastructure and starts expanding again.