Undoubtedly Ext.nd and Ext is extremely powerful! However, I am struggeling to get the overview of Ext.nd in relation to Ext, and to find the best way of learning Ext.nd/Ext.
Especially how the Domino-related classes like UIDoc and UIWorkspace etc, "hooks" into both Ext and Domino. It would be super to know more about that, so I sometime in the future could go to the fantastic Ext-demo pages and grab some demo-code and transform it into my own solutions
Unfortunately we don't have any simple overview type documentation for Ext.nd just yet. The API documentation was much improved for the Beta 1 release, but that only gets you so far. I know we had already planned to make sure we documented UIDocument and Session since those are pretty lacking. We'll definitely look into whipping up something along the lines of Ext's intro/overview docs at the top of the learn page.
For right now I would reccomend getting at least a basic understanding of Ext 2.x and the base components that we use (Tree, Grid, Toolbar, Forms). Then dig into the Ext.nd examples and the code behind them.
We had originally proposed two sessions at Lotusphere, the second was going to dive into how to customize components and more advanced use for Ext.nd, but unforunately we didn't get that one accepted.