I like the Designer 2 quite a bit. A strong product.
However, here are somethings that I noted working with the property inspector area that would make it more usable.
Add ability to set Class names for all components dropped into the project. For example, I was not able to see the ability to change Readers and Proxies class names. The defaulted class names of "MyAjaxProxy", "MyJsonReader" are cool but not helpful if many classes are in the project. I may just not know how to do this in Propery inspector so I take the blame if it is already possible.
Add highlight (bold/background color) for properties that are changed from their defaults. This is something that the Microsoft toolset does well. With many properties and large API it is not obvious which items where changed from their defaults, a means of highlighting those would be cool.
Still experimenting but very impressed.