I have a Google Fi data SIM in it and use my Gemini as a pocketable connected Android based computer.
That said, the keyboard support within Android itself needs to be redone. If you have ever connected a bluetooth or USB keyboard to an Android device, you'll quickly find things that the keyboard can do that the OS and most applications in it simply do not understand. I doubt that Planet will be able to fix those general OS issues in the Cosmo, but they are fixing a lot of other things.
The bad: The project is looking like it is going to be a few months behind schedule.
The good: The progress that they are making is looking pretty solid. They have the backlight working, rear display figured out, case & hinge hardware going into production, etc. I'm looking forward to this one - it might actually be able to be my 'all in one phone device' that the Gemini just couldn't quite be.