Thankfully it's just what most products need --a tuning release! While the Flash player did get some very good improvements (especially pixel manipulation which IMHO will be making some much more impressive stuff soon), most of the improvements were performance and stability.
The Flash 8 development environment is now much better tuned than it was. It's still got a hundred stacked child-windows everywhere, but there's now an easy way to stack the windows into tabbed panes, ala MS Visual Studio. That's perfect if you've got windows that take up a lot of space but don't need to always be showing, like help and compiler output. I've now got those set up as tabs behind the source editor. It's a little tune-up, but it does make the whole UI for the product much less unruly.
Here's a screen shot.
Other than that, most of the improvements are along the line of performance and stability tuning. They did much improve the system for developing FlashLite (baby flash for cellphone) content. They've not actually got a FlashLite runtime that runs on your PC, so you can now get a more reasonable idea of how your app will run on the phone.