I think I'll have to disagree with the majority on many counts in this thread.
Firstly, although I agree that Goblet of Fire and Order of the Phoenix should have been split up, because they were awful adaptations with awful directors (or maybe it was Michael Goldenberg's fault..). Now that they've decided to do this, I'm pretty pleased. I'm one of these fans that have to see every detail, and I annoy myself when I'm pointing out the things they've forgotton to add to screen. Heck, I think I'd only be satisfied if they acted out the book word for word, without the need for a screenplay.
So this pleases me a lot. I don't care about whether or not it is milking a cash cow or making millions for the industry. Whether or not they're selling it under the guise that they're "doing it for the fans" is good enough for me - I want as much of it as possible.
I completely disagree about the comments about Columbus as well. Claims that he is "childish" contradicts the fact that HP is childrens' fiction, so if they are childish, then I think they've hit upon its aim. I actually think Columbus was the best director, and the films have been getting progressively worse since Chamber of Secrets.. I felt the magic was captured perfectly in the Philosopher's Stone with a tight story. After the disasterous Goblet of Fire, and the alright OotP, I was unsure how I'd feel about HBP and DH, and now they've announced this.. I feel that it'll give DH a chance to appeal to the fans that have shunned the last two films which makes me come to the conclusion that this is absolutely the best thing to do...