So the Karna looks very cool. Looking forward to it. Having said that, I see 3 issues. I hesitate to even post this because i don't want to focus on the negative.
20 minute battery life.
History tells us this equals 12 to 15 minutes in the real world. However the specs also show these batteries are 75w so there is room for them to sell more powerful batteries. I bet GoPro erred on the side of safety with the batteries. Remember last year (while they were developing the Karma), the news was full of hover boards blowing up, catching fire and airlines outright banning them.
Max speed too slow for some action sports
For skiers, snow boarders, motor cross, mountain bikers, etc, 35mph max speed is not really fast enough. The Karma's portability and grip option will still make it the goto choice, but the speed will prevent them from getting high speed follow cam type shots. There are plenty of other shots they can get though. (It's not explicitly clear that follow me is even an option anyway)
If the max speed is 35, I wouldn't be surprised if that's capped at 20mph for following. I don't know that's the case, just speculating based on other drones. Anyway, 20mph would be even worse for action sports.
Fisheye lens
Come on GoPro. Who makes a drone with a fisheye lens? The software option is a poor solution. We can still fly our Hereo 4s with rectilinear replacement lenses. We don't know yet how hard it will be to modify the lens on the GoPro 5. Hopefully GoPro will release a linear lens model some day.