Google Fi is great if you never leave the US. If you spend more than 30 days outside the US, you can be penalized due to roaming, even though they have a similar offer/capability to T-Mobile for data roaming. On top of that, it's tied to your Google account, which comes with all the drama that means like the recent story about Google arbitrarily shutting everything off (including Google Fi) for the guy who took photos for his doctor.