I don't hate it and don't love it, I'd say I like it.
I tried it out whilst I was setting up and my first impression was that it was far too fiddly to get the right amount of 'press' or 'slide' to find the setting that you want, however, once I got home and tried it out again it was much easier, you just have to learn how much input to give it. It doesn't take long.
I definitely think I'll use it but probably just as a capture button on photos and a zoom control on videos. I wouldn't be upset if it didn't exist but it's definitely nice to have.
I would REALLY like it if I could use it as a sort of scroll wheel when not in the camera, I think it's perfect for that use case and although I understand it's a "camera control", I think it's worth more than that.
As for the positioning, it's definitely not perfect. It's never where you expect it to be which is a shame when Apple design is usually so intuitive. It has only been one day though and I expect the muscle memory will kick in for that pretty quickly.