I have been able to bookmark PDFs, and even search PDFs, but have to found a way to highlight in iBooks.
For highlighting, I bring the PDF into TakeNotes app, and use it as a background for a document, which lets me highlight and notate as I wish.
For highlighting, I bring the PDF into TakeNotes app, and use it as a background for a document, which lets me highlight and notate as I wish.