At the store I quickly came to realize that the Plus is rather big. It doesn't fit in the breast-pocket on any of my shirts, and that's the litmus test for me. I couldn't use the Plus as a phone because of its size, but I might buy it for another reason, which is app-development. iPhone 6 Plus is a mix between an iPad and an iPhone when it comes to screen layout of some key apps. One of those is the Mail-app, another is the Settings-app. On the Plus - held in landscape mode - those apps look like compact versions of their iPad counterparts, which means the table part is on the left and the content part is on the right. In fact for this kind of app the Plus behaves like an iPhone in portrait mode, but like an iPad in landscape mode. Clever!
The colors are the same as the iPhone 5s, except the color, say gold, covers nearly all of the back-side of the device. To me that looks better than on the iPhone 5s. See the pictures below.
Both iPhone 6 and iPhone 6 Plus are really thin devices. I came to think of the iPod touch when holding them. The iPod touch is still thinner at 6.1 millimeters, iPhone 6 is 6.9 millimeters. Both the new iPhones feel very light, 172 grams and 129 grams. BTW while I'm mentioning iPod touch, I note that it's come down in price, putting it far below iPad mini. I should be put in charge of Apple's pricing, because I blogged earlier about pricing the iPod touch so close to the iPad mini (non-retina version). Now Apple has corrected that.
I didn't buy a phone today after all, but having held both options in my hand, I'm going to be able to make a more informed choice. I'll wait a couple of days.