Everything worked great with it for the first few months, but then I started getting severe speed drops - specifically I was seeing download rates of 20MBps or less, when I should be getting 350MBps or less. I did all of their recommended troubleshooting (reset router, reset modem, restore to factory settings and reupdate the firmware, move router away from potential sources of interference, etc) and could not solve the issue. I still had my Nighthawk and ended up spending an afternoon testing the two, and the Google WiFi router would consistently drop speeds, while the Nighthawk stayed rock solid.
I ended up just sticking with my Nighthawk and throwing my Google Wifi in a drawer. I was outside their return window, and honestly just had no desire to try and go through Google's customer service (or finding out if it even exists for their WiFi devices). Long story short, it was the worst experience I've ever had with a router and I would hesitate to ever try their WiFi devices again.