The Santa Clara Microsoft store (near Apple's headquarters!) also said that this rear camera issue is a software issue. They told me to wait a week for a possible firmware fix, so it is great that you posted your experience!
My "bad camera" unit has locked up on occasion and always on web surfing. The pen has stopped working on occasion and has a real hard time pairing with OneNote.
I also wanted an Apple iPad to run OS X and on my PC, skipped Windows 8 & 8.1, waiting for MS to get the desktop / tablet balance figured out. With Windows 10, they did just that & so I waited for what the iPad Pro & Surface Pro 4 features & specs were going to be.
Tim Cook announced the iPad Pro with variable touch sensitivity but running on iOS. He stated that a hybrid Mac/iPad was like mixing a refrigerator with a toaster. Bad move on his part, because like you, I was waiting for the refrigerator/toaster hybrid and am NOT an Apple only/MS only/Android only consumer!
I am happy with the Surface Pro 4 as the hybrid balance is just right. I fully expected some of these issues due to the rush to market. I have waited in those iPhone lines waiting for a product that can't run effectively until a month after you buy it! I will wait it out this week without a rear camera and will try and return it if there is no firmware update.
BTW, MS Maps is not showing a graphical representation of the streets, just the street names! Is this also what you are seeing on the Surface Pro 4?