I got a feeling of claustrophobia. George Orwell goes to great lengths to inform his readers of the incredible oversight capabilities of Big Brother and the Party. The people in the story are not able to have a moment to themselves. They are watched every minute of every day. In order to sell that mood of claustrophobia, Orwell tells his readers that there are cameras everywhere, even in the bathrooms. There are cameras on the streets, bedrooms, bathrooms, restaurants, etc. Every minute of every day, the people of Oceania can assume that they are being watched. Orwell even tells his readers that personal thoughts are no longer personal, because the Though Police exist.
I also got the feeling of hopelessness. With so much oversight, it's next to impossible for anybody to rebel in any way. People can't organize. People can't say anything remotely anti-Party. People technically can't even think about it. On top of that are some little things. Not only are people's independent thoughts or hopes and dreams being quashed, but also the language that they could express themselves with is being diminished. A big part of that hopeless mood comes at the end of the book. The reader has hope for Winston and Julia (for a bit), but the Party wins in the end. Winston is a mindless automaton of Party support. The reader is left feeling that everything Winston did was for naught.