Ugh... it's not just the quick entry box that's changed. I'm unable to hit return to add a new action in the project mode if I'm in a field other than the action name (e.g. context).
Please please fix this guys!
BTW, I'd like to suggest a corollary to the "return always starts a new item" rule, and that is, if an item loses focus without any entry, it automatically uncreates. So, if I have a project, and hit return, and enter "task", and then hit return, I have created two children, one named "task" and one empty. If I click elsewhere, the empty one should simply disappear.