I'm trying out the DOM for 2.4... and I have a bug that just makes it useless. I'm not sure if anyone else is getting it 'cause it's an issue too serious not to be mentioned anywhere in the forum.
When you try and add something, a lightbox appears for the DataObject's fields..... the problem is everything behind the lightbox disappears... well, you still see a wee bit of the interface, just a sliver on top. The fix is to just open firebug, and close it again, and you'll see the rest of the CMS.
I get an error in the console saying $() is not defined, looks like a jQuery error, but, I checked and jQuery is being loaded. I'm using the latest release r399.