I've been learning a little about Flex 2 this weekend while working through O'Reilly's Programming Flex 2 by Chafic Kazoun and Joey Lott. There's always a big gap between working through a book and doing a real project when it comes to technology.
That said, one feature of Flex 2 that I think is implemented quite well is states. From my practice, it seems Adobe has implemented the concept in a straightforward manner. States relate to the view. You create different states for different modes your program is in. A program can only have one current state at a time. I'm impressed at how easy it is to set up a series of states and switch between them. When you do switch between states, the different controls on a state preserves its own state, i.e. a checked CheckBox remains checked whether it is part of the active state or not. I look forward to seeing whether I feel the same in actual practice.