Just checked them both out at the Upper West Side Apple store here in NYC....and there aint NO way I'd get either of them without a silicone case. They're beautiful as hell...but are just so curvy and damn slippery. The plus popped out of my hands three times. Once falling on the display table. And I've got big hands.
I like both. The 6 is the perfect hand/pocket size. But the screen on the plus is just so friggin gorgeous.