I'll admit it - I had to peel off my iPhone case and glance at the back to see exactly where the Apple logo was situated. And, admittedly, to even see if there was an Apple logo at all! I would have been no less surprised to have seen just a text iPhone logo. So, this logo placement change is not a huge thing in my book, but good on Apple for innovating for once.
Also, speaking of cases - this device-to-device charging feature, I wonder how it will work (or not) with a case on. I'd imagine the feature works flawlessly without one but can see a case hampering the efficiency.