yeah, it's an adjustment. I really liked the size of the 5/5s, but the 6 just has a much easier screen to use and enjoy...
one thing that actually happened to me was when moving to the iphone 6, I started to put my pinky UNDER the bottom of the phone for support. Over time, I started to get a pain in my forearm and elbow. Turns on, putting the pinky under the phone was straining some tendon under the forearm that went all the way up to the elbow. It took several weeks to retrain my behaviour but now after a month it's nearly gone. so, be careful how you hold it. ;-)