I've been with Fi for 3-4 years now. Inside the city is is amazing and works great. Outside in the sticks, it will depend on what cell tower you connect to and how hard they are throttling data from third party companies.
You need a google phone, and have to verify that your phone will work on their software.
The downside is that if there is an open wifi, the phone will grab that, create a VPN tunnel to Mountain View, CA using that as your location in any web browser. If you turn off WiFi on the phone you negate the good parts of using Fi. kleinbl00 had some trouble with the WiFi component and he can give a better negative than I can.
Note on my use: I make 3-5 phone calls a day, get under 10 text messages a day and use the phone as an email viewer, an RDP to my servers, tethering my laptop at events, and some space/astronomy apps. Total bill a month comes to under $30. The most my bill has run over the last year with the Pixel 2 phone has been $40, and that was due to me tethering a laptop out in the sticks and needing to upload images and Powerpoints to a school. Last month's bill was $27.
Go find the TMobile connectivity map for where you live, and look at where you go compared to the signal strength. If everything there is green, you should be good. I've noted that the Pixel 2 seems to have a better 4G antenna than the other people in the office; they will have two bars and I will be at full strength, for example, and that is assuming I do not grab a WiFi and negate the need for a cell tower at all.
One bonus is that with the Google branded phones you don't get any bloatware. You get updates to your Android version and security updates for three years, and you get them before anyone else on an LG, Samsung etc phone.
And if you have a credit score over 750 you can get 0% financing for two years in most cases, but that is no longer a plus as all the carriers will offer some form of "Please pay us a monthly fee as that is where we make our margins" financing plan.