Controversy notwithstanding, Rowling just isn't that fabulous a writer.
It's difficult to say that because I enjoyed the Harry Potter series just as much as the next person, however, there was clearly more to HP than a bunch of well-written characters. Because Rowling does know how to create characters we care a great deal for. It's the plot part that seems not well thought out.
Or, perhaps, it's too well thought out. I got bogged down so often in the incredibly complex details of who was where when and why. At times, I felt that the book was an exercise in memorization, and perhaps there would be a test at the end ("Please list three names in the book that began with R".) In some ways, I wondered if Rowling was obscuring through detail. As if she was thinking: "Hey, I'll make you forget why I created that character with dyslexia because I've just thrown a zillion names and places and dates at you. You're bound to forget!" This seems a disingenuous way to move a plot forward, and especially to get to the end of a plot.
Part of me does want to find out what happens to Cormoran and Robin, but most of me does not. If you absolutely loved the next two books, make me a case for reading them.