I'll admit that the camera on the new iPhone 6 is nicer, that the display looks slightly better, and that it responds slightly faster.
Is that enough to get me to spend $300 to upgrade? Nope. I'd just be exchanging one large screen 4G smartphone for a slightly newer one. My Samsung Galaxy S3 still has a lot of life left in it, especially considering that I can replace the battery if it goes bad or add additional storage if I run out.