I have mentioned this in another thread, but unless Apple come up with something as aesthetically pleasing as the S3, they are going to have a hard road ahead I think. Being lucky enough to own both, I can say that when I look at my iPhone after a day with my S3, it looks very dated. The build quality is far superior on the iPhone, Samsung didn't really wow me in this department, but overall the S3 feels a few years ahead of the iPhone.
I think what is most frustrating to consumers is Apples slow, minor updates that they do to their line of products. They need to start wowing the consumer more. Gone are the days where Apple was revolutionary. They are now competitors rather than innovators. Its all been done, so no one is going to fall off their seat when you release a new model that looks exactly the same and has slightly better insides. Don't get me wrong, I LOVE Apple products, they are solid well built machines, but unless they blow some socks off with the iPhone 5 I don't think that many people are going to hang around using their phones.