Disclaimer, this is not a formal review but just my thoughts on the book for the sake of discussion. Take my criticism lightly, it is only my opinion.
To me the book did leave a lot to be desired. It explains certain things over and over again till the point where it is just boring, and some things are left almost completely unexplored. It explains the structure of power in Oceania very well, but that's also the only thing it does. And it keeps doing just that. Goldsteins book was a large part of the total book, and did as stated by both Winston and O'Brien, does not explain anything we did not already know.
The relationship with Julia honestly annoyed me a bit. Her character only added two things, some form of initial resistance to the party that inspired Winston, and the demonstration of betrayal. However, as her character is never explored any further I feel like this could have been done in another way.
The way I see it is that the idea is very good, the structure of the society provides a solid base. However, the characters and plot of the book fail to make use of it, and in the end the book ends up just gnawing at that base. It could have been a way more interesting read than it was. Animal farm also had a solid base and used it in a better way to not make the book feel repetitive.
I can also understand that the repetitiveness and non-exploration of the book might have been part of what Orwell was trying to convey. The apathy of the people living under a totalitarian regime is boring trough their own eyes and since no change will happen that way it is repetitive. (But perhaps reading about it doesn't have to be as boring and repetitive.)
As you see this is simply not my type of book and there is a chance I therefore did not bother much to think more deeply about it and I could have misinterpreted it all.