It was definitely a learning curve for me too, but I'm now happily using the new themes structure.

The only issues I still have are:
- the slow compile process (about 15secs using sencha ant sass theme)
- resources don't compile from the package/theme

But both of these I can live with

That was a few weeks ago now so of course my recollection of the exact issues that stumped me are hazy, but in case it helps I've looked back in my forum history and these are the threads I posted in (if I posted there then they must have been useful to me ;-) ):

http://www.sencha.com/forum/showthre...uilding-themes
http://www.sencha.com/forum/showthre...om)-components
http://www.sencha.com/forum/showthre...-CSS-compiling
http://www.sencha.com/forum/showthre...e-parent-theme
http://www.sencha.com/forum/showthre...uild-resources