There's no doubt that Cook is no Jobs, but I think he tends to be underestimated. There are thousands of MBA holding, business as usual, 'shareholder value' type CEOs out there and Jobs could have had any dozen of them. Apple was far too important to him to have left it in the hands of one of those guys.
Not saying this applies to you Sue, but a lot of people here who discount him seem to be saying that Jobs was a visionary genius who somehow managed, after studying succession carefully including looking to Disney as a great example of a business that prospered after the death of its founding visionary, to completely stuff it up and leave it in the hands of some supply chain numpty who only cares about the bottom line. Based on Apple's performance and in spite of the lack of excitement of late, which disappoints me as much as anyone, it just seems to be unsupportable position. Jobs was too smart and cared too much to have done that and Cook would never have been in that position at Apple if that's all he ha going for him.
It's very difficult to imagine Jobs appointing someone who would ditch a brilliant person because he was a career threat. That's something a man-child like Drumpf would do; Cook shows no signs of being an easily threatened toddler. No, anyone in a C level position at Apple knows they have to negotiate the challenging path of allowing the next Jobs to come up if and when s/he arrives. They all need successors too and making sure you've got a good replacement is part of your job at that level. I heard that Forstall was very divisive and that refusing to take responsibility for the Maps debacle was the hill he died on. If he's any good we will hear from him again.
Apple would kill for a great keynote speaker again. They would have put up with heaps of shit from Forstall if he was that guy because it would have been worth it. It looks like he must have been pretty toxic.