Well, it's open, the giant commercial celebration of everything that is Harry potter. No doubt your kids (or even you) are clamouring to go along to visit.
I just watched a short BBC report on the first day, with an obviously unfilmed segment on the rides (to not spoil the surprise) and onto the locations and shopping to be done.
Hermione's wand: $30
Wizards cloak: $100
HP's broomstick: $300
All sold out on the first day!!!
Apparently the Butterbeer was quite tasty, and the nastier sweets lived up to their name!
20 acres? Is that really big enough? We will see over the coming years as the final films come out and people are still reading the books and buying the DVD's. This isn't over yet, not for a long time.