I am reliably told that the style of questioning and the questions themselves have changed significantly from the old iteration.
Certainly with the introduction of online exams there has been a change to the style and format of questions. The information that you need to know to effectively exercise the privileges of a PPL has not changed so any of the traditional sources should still suffice.
It has become common practice to only learn what is going to be examined and the questions certainly would not have won any prizes.
The CAA has published a document containing a revised PPL Syllabus, like most that have gone before it its an old style list of items that is supposed to represent a syllabus, but lacks any detail regarding depth of knowledge. It resembles the stuff the RAF threw out in the mid 70s.
CAP1298 Rumour has it the latest questions are based upon this syllabus.
The main EASA syllabus can be found in the
UK Aircrew Regulation at AMC1 to FCL210 FCL.215 Theoretical Training.
In theory, if you know your stuff, you should be able to pass any question they throw at you however; over the years I have seen many questions that have instructors scratching their heads..