Nokia sells more handsets than any other manufacturer in the world. Who has not ever had a Nokia? Look at your chargers drawer and you will find one or two Nokia chargers. They have been very successful so far but there is a “but” here, they do not seem to be the industry visionary, they look more like the big fish who will follow other's innovation trend and mirror their successful products. I am sure some bells are ringing in Nokia's strategy steering committees, they do need Marketing driver, something that makes customers to feel identified to the brand, something that makes a difference and keep customers loyal to their products.
Maybe, a key differentiator is one can buy and use all Apple's products (iPod, iPhone, Mac, …) but there is no way you will do same with all Nokia products, unless you are manager of a mobile's shop ;-) When Nokia launches a new product there is not big expectation unlike Apple's product launch big shows chaired by the great Steve Jobs.
Nokia products are, most of the time, excellent quality and worth the price but customers don't come the shop with the purpose of buying a Nokia but the one they favourite, happens to be a Nokia handset. That makes Nokia their own worst competitor, the quality / price ratio is the measure of the their success and if they launch a handset with that ratio lower than average, it will become an immediate failure.