After taking an afternoon to test Beta 2 on a complex UI design I have some suggestions:
1. You need to add the ability to create masks. I understand there are some work arounds, but masks should be a non-trivial add especially considering how easy they are to use in Flex. I suggest allowing the user to identify an object as a mask (either something created with the drawing tools available in Catalyst, or using imported assets). Then the user can associate objects to be masked with a mask (perhaps via a drop down list containing available masks). You should be able to select a single object or group of objects to be masked.
2. Text alignment. I don't understand why the ability to align text (left, center, and right) is not in this beta. Also 'point text' and 'area text' are not very intuitive.
3. Scrollable lists (using direct manipulation, not scroll bars). This one is a bit more complex so I can see why it probably hasn't been implemented yet. I thought Scroll Panel would do this, but it doesn't. The desired behavior is to have something like Data List for example but you can use the mouse (and ideally touch if the target platform is a touch enabled device) to directly scroll the content. Maybe the user could define dragging bounds and then be able to drag/scroll an object within these bounds.
Since I'm also a developer I have a few suggestions that can make the output a bit more developer friendly. One thing that would be awesome is the ability to select a skinned component and export the code for that component. This would allow designers or developers to skin components in Catalyst and then export the code for that component and hand it off to a developer. Currenlty I would have to cut and paste everything out of the single file exported by Catalyst (which is not an ideal workflow for any developer I know). One of the drivers here is that visual designers don't really think in terms of components (well I'm sure some may), they approach a composition as layers of visual elements. Therefore I don't think many visual designers will be able to effectively use Catalyst. Someone like myself, however who is an interaction designer and also a developer could really get a lot out of Catalyst. For a wire-frame oriented exercise I'd use Catalyst to add interactive elements in order to better show intended transitions and ui behaviors and simple share the swf or AIR app with the client for feedback. However for a high-fidelity prototype I would inherit polished graphics (that are also likely going to change during the development process) from a visual designer. In this case if I could use Catalyst to skin the components, export the code for the individual components (as separate classes) and then use that code in my Flex project that would be a dream. What would be even better is once I have skinned a component in catalyst, if the visual designer changes something I can get the new file and update the component automatically due to the (linking between Illustrator or Photoshop and Catalyst), export the code and bring it back into Flex/Flash Builder, effectively changing the visual design without having to make major adjustments to the code. The current way code is exported from Catalyst doesn't help at all unless my only intent would be to add a little extra interactivity. There is a whole other use case for Catalyst that seems mostly unaddressed.