I like a first paragraph that drops a person into the story, but gives enough information that makes you want to learn more about this person. In medias res can work sometimes, but to much bopping back and forth between the past, the present and the future (Anne Rice, are you listening?;-) gets under my skin and irritates the crap out of me. I want a beginning that engages me and makes me want to know more, but doesn't leave me confused as to what is going on and who is who.
challenging authors not to put in backstory for the first 50 pgs. Yet, his best known client, begins his series with a 60 year old man telling us he's writing his story- (that's backstory right there) he goes into the story of a battle- within a few pages backtracks to tell us how he met the commander.
By the time he finishes that huge passage set on another continent, and goes back to that first battle sequence, I was like- what? where are we? And I am a very patient reader. I don't have to be grabbed right away. But the ENTIRE first 50 pages was nothing but bactracking backstory.
It makes me want to scream- get off your highhorse dude!