@Adam_Qwert_Nayana: Yes you need to calibrate each time. Not sure about the other trainers (Kickr, Neo), but I think they also need a calibration… At least occasionally, as belts loosen up over time of use.
Yes, you can use the R1 as a “stand-alone” unplugged trainer (i.e. for warm-ups prior to an actual race, out in the real world is the most common reason that I see for this - You can apparently set a resistance level in the app prior to unplugging and heading off, but I have not checked into this, yet).
General feelings: I like it. Now, having said that, I have pretty much no experience on other wheel-off or even smart trainers… After several reviews, I leaned towards the R1 as it allows the rocking motion, that I was accustomed to from my Rock & Roll fluid trainer, AND off course it is less pricey than the Kickr.
@_Nightyear: Yup, I looked at the TacX Neo as well… Definitely a cool set-up there. Hadn’t read that they are zero-calibration. Yeah, the spin down calibrations are apparently due to the wear/stretching of the belts, etc… over time. The actual calibrations take very little time… I quick peddle up to about 40KMpH, then coast down to stop - So maybe 30 seconds. Though you should warm the trainers up first for about 10 mins (give or take) --> Basically do your own regular warm-up on the bike, then do the calibration, and go! So not a huge inconvenience, but I hear you about just wanting to go.