Has anybody with a Nexus smartphone tried out Project Fi? It is a relatively new cell service that automatically connects you to the stronger signal from Sprint, T-Mobile, or US cellular. What makes it a bit different is that it also automatically connects to decent public Wifi spots as well as your home Wifi(after one-time key in) and allows you to call and text from Wifi as well as cell signal, whichever is stronger. It is $20 per month for unlimited calls/text and $10 per GB cell data and it refunds any unused data proportionally. Wifi usage never counts towards data.
My main interest is what you think about the service or model, though you could also comment on what aspect of the Nexus 5X/6P is good or bad.