Pessimistic, matter-of-fact, sharp
1984 is written in a gloomy tone, with a very matter-of-fact, unornamented style. There's little color to the novel. Neither eloquent prose nor slapstick puns would fit the bill here. The environment is dismal; speech is restricted. Kind of like the text itself. This is more of the "Orwell makes you experience Winston's experiences" deal.
The style is rather uniform, except for the long political tirade from Goldstein's manifesto that is written in a different fashion. It read like a manifesto...as you might expect.