When I write Norwegian, I use proofreaders in order to place punctuation correctly (I never mastered that trick) and check if I have done any of my common errors, like placing the last letter of the word at the beginning of the next, or using dialect based expressions in my rather formal written Norwegian. I am stilistically quite advanced in my own language, and there's rarely any need for the proofreader to restructure a sentence or find a synonym. This is why I, despite the differentiated types of writing I do in Norwegian, was not prepared to what happened when I got a proofreader for the thesis. After the first few chapters he has obviously grasped both my style and the topic. He has figured out the jargon he shouldn't correct, and he understands where I want to go and what I want to say. Right now I am going through chapter six, and as I click on the "accept changes" button over and over again, I am amazed. I sound eloquent, the sentences are elegantly shaped - in general: I appear more intelligent than I ever thought I could be!
While going through the text and the million little and large alteration in order to make certain that I can agree with what I have written, I praise what ever lucky star directed me towards this man. Proofreading. It's great!