The bit I don't understand (as someone who's not super knowledgeable about the inner workings of computers) is why this isn't the same situation as the PS3. PS3 had wildly different architecture to PC's. This made it difficult to develop for which lead to a lot of that consoles problems. This time round they're closer to a PC style architecture than before, but rather having separate graphics memory and RAM, they're having 8GB of GDDR5 shared between the two. Surely, like the PS3 before it, leads to a different architecture that developers have to learn and makes development difficult?
Developers are all talking highly about this thing and how easy it is to develop for, so I assume this is just my ignorance of not understanding how computers work.