I’ve been using it the past week and it’s terrible.
The moment I activated it (new number, did not port), it has been non stop robo calls and texts. The visual voicemail has to go through the Google Fi App and doesn’t always transcribes messages. SMS messages were initially flaky but worked themselves out.
I have already canceled it and am using a T-Mobile pre paid sim for the moment. The coverage still sucks, which depletes my battery, but no spam calls or message so far.