Glad you share our enthusiasm on the project.
Here are some things you have to keep in mind though.
Dimp Preview is, as the name suggests, simply a Preview of what's to come. This means that you get limited features, such as:
With that in mind, the Preview has been released simply to give you a feel of how animating with joints and frameworks will work with Dimp and on the Mac, to let you familiarize yourself with some of the features that will not change [much, for now] in Dimp (such as the way "frames" are replaced", and finally to give you a taste of our approach to the task.
I hope you enjoy yourself and are able to find amusement for now with the simplified Preview.
The Public Preview is in a sense a public Beta, and any additional and really useful tips, bug-discoveries or such will be greatly appreciated!
Have fun. 
~ Sean