It's the easiest thing in the world to take some pieces of badly-written English (psychology research, art reviews) and jeer at them. However, when the jeerer is George Orwell, you sit up and take notice.
Some of the advice to writers is a bit out-dated. Most professional authors will know that using long words and sentences isn't a good thing and enlisting the King James bible as a model of succinct English won't convince many current sloppy writers to reform. However, it doesn't hurt to be reminded of these things and I particularly liked the inclusion of a review of Mein Kampf, showing Orwell putting his literary ideas into action.