I meant "difficult" more in terms of lyrics (and even vocals). Some people don't feel comfortable with the artist they listen to presenting himself so naked and vulnerable on record. And John was never more naked (insert 'Two Virgins' joke) and vulnerable than on 'Plastic Ono Band' in my opinion. Other listeners disagree with the statements made in 'God' which is another point of polarity. As I said, it is weird to me that people have held the album in such high regard over the years, because in my listening experience these are the albums that split opinions to the most extreme degrees.
Yes, John was brutally sincere in POB, but I see the album just as an instant photograph of John in 1970, different from the John that lived before and after that year. So in 1970 John was an unbeliever and not a dreamer, but briefly after he was able to imagine all the people living life in peace and asked people to play mind games together. So I don't see POB as a reflect of the true John, but as the image of the lost John. And maybe that's why POB is able to capture the public.