I have always been impressed with Flex back when it was called 'Royale' and when the IDE was referred to as 'Brady'. The concept was very appropriate for Macromedia with its Flash flagship; it appears as Adobe attempts to further assert itself into more than just tools for graphic designers, Flex will continue to be appropriate in the Web 2.0 generation (I hate the 'Web 2.0' moniker - oh well). What is interesting about the toolset is its positioning of the proprietary ActionScript scripting language.
These are interesting times to be in technology. In terms of the delivering end-user applications there appear to be two platforms that can be developed upon: Windows, and the Web. The vendor race is on to win the hearts of developers in terms of what tools and platform are going to deliver the best experience.