I've been a flash developer ever since Macromedia bought Flash from FutureSplash. When Adobe took it over after Flash 8, CS3 and CS4 has brought some great things, and brought some colossal headaches.
Things they've done right:
- Actionscript 3.0
- Tight integration with design tools. (Creative Suite)
- Flash player improvements
Things they've done wrong:
- IDE is more bloated, and harder to work with
- Motion editor