Jason Snell at Sixcolors:

I’m not saying the iPhone 6 Plus is wrong for not being an iPad. Not at all. What I’m saying is, it’s not an iPad—and that I think people who expect it to be one are going to be disappointed. If the question is, “Big iPhone or small iPad?”, the answer is clear: The iPhone 6 Plus is called iPhone for a reason, and it’s not the Phone app. Choose your preferred iPhone model with that in mind.

I am going to order an iPhone 6, but for a few days I toyed with the idea of getting a 6 Plus and ditch my iPad. It is a wrong idea — and very un-Apple for that matter — to assume that a single device can replace both an iPhone and an iPad. 

The whole point of the iPad was to have a device that was way better than an iPhone and a Mac, in certain context and for certain tasks.