After a day of intensive testing in our labs and in the field, we can share some of our results with you now: The iPhone 5 fulfills its promise as a notable—though not dramatic—improvement over its fine predecessor, the iPhone 4S, and belongs in the first rank of smart phones. That's in spite of a mapping app that's disappointing, at least so far.

Our tests continue—and our testers (and shoppers) all could use a nap right about now! But here's a quick synopsis of our findings to date.

It looks and feels different. The iPhone 5's screen is longer than that on past iPhones, and the extra depth of its (16:9) screen allows you, for example, to see an additional row of app icons.

The display is equally fine. The iPhone 5 retains the Retina display technology employed on the iPhone 4S, and the screen looked equally crisp and bright to Mike.

It's much faster to load content, as expected. The addition of 4G LTE capability to this iPhone 5, along with its upgraded processor, paid off in spades during Mike's informal tests today on Verizon versions of the iPhone 4S and 5.

Apple Maps falls short of expectations. Unfortunately, as Consumer Reports' Cars deputy editor Jeff Bartlett has reported, the potential of Maps remains unfulfilled.

The camera is a modest step up. The camera on the iPhone 5 performed better than that of the iPhone 4S, in a number of tests today by our camera experts.

For full details on our test results, see our full review at ConsumerReports.org. We will continue to test the iPhone 5, and we'll report back on the results through next week.

—Mike Gikas and Paul Reynolds