I think if you read through the thread, a number of people are experiencing a common problem with the iPhone 5 that they haven't previously experienced with their previous iPhones. When you spend this amount of money, and your previous experiences of Apple are almost all positive, it is genuinely frustrating and disappointing to encounter a problem with heat and excessive battery drain - moreso when you can't seem to find a definitive answer to resolve the problem. I read the threads (also across a multitude of other sites) and was irritated that someone with a high post count (modular747) should reply to some of the postings here in the manner that he/she did. It is wrong to reply to someone seeking help that it is YOUR phone when a cursory search of the internet reveals this to be a widespread problem - and comparing it to the sales rate of the phone isn't really relevant if there is a high residual percentage of people desperately seeking assistance. I am called a troll for taking exception to the tone of someone's replies - someone who should clearly know better given their extensive experience of this board. I am also called Mr. Zero - along with some other posters - when all I/we have done is visit this board to seek some assistance. Who is in the wrong here - very occasional posters seeking assistance for an unwanted problem - or an experienced practitioner on this board replying as he/she has. As it happens, my iPhone 5 is no longer running hot. The problem was resolved by implementing a number of suggestions across a number of the forums.
I first reset the phone to factory settings in order to start again. I reinstalled everything from back-up. This didn't seem to resolve the problem. So, I started again - reset to factory settings and then installed everything as a new phone - a bit slow, a bit laborious, seemed to be slightly better but I was still not happy. I presumed that somehow, my settings were causing the phone to be in use - even when I thought the phone was pretty much in sleep mode - I presumed the battery heat and excessive drainage were because my phone was a lot more active in the background than I believed it to be.
Back to the drawing board - reset to factory settings - install as a new phone - and then look at the battery saving steps in the zdnet article referred to previously. I went through them. I think if I could summarise what I've done, I have more or less made the iPhone 5 a device that speaks to me only when I manually ask for information. I've disabled location services, background apps, push email, iTunes match, and a number of iCloud services that sync across multiple devices. And my last step was to disable 4G/LTE.
Much to my delight and relief, I found myself with an iPhone that seemed to have a pretty normal battery life and that no longer ran hot. Have I lost out on functionality - yes and no - I no longer have real time updates on stock prices - but I can retrieve them manually when I want to see them: I no longer use iCloud to be the source of my 132Gb of songs (I just manually load those albums I want to hear); I sync Contacts across iCloud only manually; I don't receive emails unless I ask to see them; I don't use Maps anyway; and when I do want to run software that needs to have Background Apps such as Runkeeper, I switch it on for the required period. As for 4G/LTE, I don't notice any significant loss in speed - but I do notice that I don't have a hot phone. One last thing I have found, when in a country with less reliable reception, I selected a network manually - and if I moved and lost that network, I manually selected another one. I didn't leave it on Automatic. It seemed to help.
I have no definitive answer to offer on the problem with the phone - but my experience suggests that it is not a hardware issue and hence replacing the phone is almost certainly not going to resolve the problem. My experience also suggests that the phone runs hot because it is a lot more active than any casual user would believe it to be. Hence it is draining the battery, heating up and draining the battery more. It seemed that by being more concious of Applications that were prone to keep the phone "busy", led to a better outcome to overcome this problem. Some people have reported problems with restoring from back-up - I didn't take all the steps to cut down on Background Apps - so perhaps back-up isn't an issue and the root of the problem is that the phone design doesn't lend itself well to all of the Background Apps being left on.
As for modular 747 - I did read the zdnet article (and implemented almost all of the suggestions) and I found it helpful for the reasons stated above; knowing 50+ iPhone owners really doesn't explain why a Google search reveals this heating issue to be commonplace across many users; your forum count suggests you have previously been helpful - but not so much on this thread - and I've read every post; and if you take pride in deriding people with "Mr Zero" tags, what can I say in the face of such maturity. In fact, it is very telling that this thread has a number of "Mr Zeroes" on it - could it be that we have not previously had problems with our Apple purchases?
The thing that worked for me was to presume that my battery was working harder than I intended or needed - by taking steps to make more of the Applications operate in manual mode, and to cut down on network searches for the best reception, I no longer have a hot phone. I hope this may help others.