I used full-screen notes mode a lot in OF1 for iPad, and just discovered that it’s gone in OF2.
It’s a especially problem in landscape mode as only half of the screen becomes effectively available for notes. Much less a problem in portrait mode, though.
Support replied that it’s done intentionally–so if you miss the OF1 full-screen notes mode / if current half-screen is not enough, please email the omnifocus@omnigroup.com asking to reconsider the removal of the feature.