I have had many great appointments with Dr. O'Neill and highly recommend him, but I don't think Dr. John makes a great stand-in. His bedside manner is extremely lacking. He's very cold and short, his adjustments feel hasty and not thorough, and he doesn't have a ton of great suggestions for aftercare or home exercises. He left off my appointment essentially saying "maybe this helped, maybe it didn't" -- not reassuring when I'm paying out of pocket for the appointment. I'd absolutely recommend Dr. O'Neill to a friend, but if Dr. John is in the office, I would suggest looking elsewhere unless it's an emergency.