Pros: Catalyst is very easy to use. New state model and Spark skinning simplifies coding. New Builder tools help debugging efforts. Good client-side data management additions.
Cons: Catalyst lacks advanced components; transitions are awkward to apply. Network Monitor monitors services calls (Flex RPC) only.
I liked the ability to isolate code by page (or state) in the Flash Builder 4 IDE (known as Gumbo). Because a single Catalyst FXP file contains the code for every state of the entire interface, it can become cluttered. To streamline navigation and comprehension of the design, developers can isolate by state and view only the code relevant to the page they're working on. I'd like to see the code actually collapse too, rather than just gray out.
Flash Builder 4 brings new tools to data-centric workflows, rounding out the coding and design focus of its predecessor, Flex Builder 3. Builder 4's new data service wizard makes very quick work of importing and introspecting back-end services and binding them to UI objects. In addition to PHP, Web services, and HTTP services, Builder also supports BlazeDS, LiveCycle Data Services, and ColdFusion.
Just by dragging and dropping, I was able to take a standard query function on my data source, import it into Builder, and bind the result to a data grid in my Flex UI in no time at all. Builder inserted the code that manages behind-the-scenes data fetches, as well as the updates between my master/detail paging. I could even choose to track changes to the local data store, and undo changes before manually committing updates to the server, reducing the number of round trips. This is a great improvement for interacting with large data sets via a Flash GUI.
Builder's new package explorer is also a leap forward from previous versions, providing easy drill-down into all of your libraries, services, ActionScript, MXML, and page assets from a single view. Heightened help facilities and code hinting now sport much richer detail and live ASDoc support too.
Say good-bye to those kludge traces on network calls, thanks to the addition of Network Monitor, which captures and displays live traffic feeding your Flash player. Access to request parameters, response packets, roundtrip completion time, and other useful details make debugging complex data calls much easier.
A final perk worth mentioning is the addition of unit testing. Builder 4 brings point-and-click simplicity to the creation of unit test classes. You can drill into a package, select a method, and create a test class for immediate feedback on code errors. After you fix those errors, the new Run Failed Tests option takes the tedium out of testing by rerunning only the important bits -- a real time-saver.
There's more to like in the Flex 4 SDK as well. At first glance, a new animation class and 3-D support, a new component skinning model, and improved text display capabilities look quite good. We'll have more to say on these and other Flex 4, Flash Builder 4, and Flash Catalyst goodies as Adobe approaches final release.