Although calls on my series 1 are fine,AEBE, I think that is the idea. It isn't meant to be a primary call device*, but is really nice to have when you are away from your phone, like say, out in the garage, under the car, or out in the yard when a call comes in. Beats having to hoof it back inside to take that call... It's gotten to the point that I only answer calls on the watch if absolutely necessary.
*Wild card are AirPods. I was floored how clear phone call are on the AirPods over my phone. They sycn to Apple Watches too. If you can genuinely wear your Airpods and take calls over your watch with similar clarity, then THAT will really be something and one step closer to leaving the phone on the charger more often.