If your not happy with it why keep using the phone , make the appointment nowI've never restored from backups. Habit back from my Android days. Always felt corrupt data would ruin my experience. Yeah, I'm not liking this but I think I'll stick it out and see if it gets worse. I need to be able to replicate it to an Apple specialist.
Even then, I run the risk of getting the same problem in a new device. That or getting something worse. Hmm....
If you tell them you did a fresh install and still keeps freezing from time to time and there's no way to recreate this live , unless the genius is a douchebag there's no way they are going to say no to you for a replacement , the phone is less then a week old