Worked for me :)

I initially tried using this on the iPhone5, and, like others have said, it didnt work because of the headphones jack being on the bottom of the phone near the mic. Luckily, I have my old iPhone 4, so I downloaded it on there.
My purpose for using it was to hear my babys heartbeat. Im 28 weeks pregnant, so I knew it couldnt be too difficult to find. Not that this has anything to do with the app itself, but in case an expecting mother happens to come across this, Ill add that I wasnt able to get a read on babys heartbeat while sitting up in a chair, so I laid on my back and was able to detect it in less than five minutes.
I was also able to record it which was a HUGE bonus! Im only giving this app four stars because the look of it is dated and it should warn people with iPhone 5s and up that it may not work for them due to technicalities, but otherwise its great :)

beanpiii about iStethoscope Expert