First and foremost, Mark Watney is an intelligent cheeky little shit who gets stranded on the Red planet. 
 Mark Watney is smart, snarky and witty, has a strong sense of self-preservation and has the calmness to plan to survive on the very place that's actively trying to kill him. His long entries lose the sense of professionalism when he realizes the predicament he has found himself in. 
 Nothing is easy for Watney as he uses every part of his academia as he plans for a long term goal - stay in mars for about four years till the next mission arrives. And then he gets to work: food, water, power, communication etc. He learns it the hard way - everything he has learned in theory is put into test and he pretty much writes the guide for "what to do when you are stranded alone on an planet with two degrees, no communication to earth and copious amount of sarcasm." 
 From there its tackling one small goal after another. And like Watney says somewhere along this line "...and then there will be an eventual fuck up because knowing me, it will happen." And it happens to him. And every time things go haywire, he finds an alternative to survive. 
 If you are expecting emotional monologues, realism of high improbability of survival on Mars, over compensating characters - this book won't bend its knees to achieve that. The secondary characters don't stand out; they all seem to have a standard protocol-ish existence in the story and quite easily forgettable. 
 This book is hard sci-fi, good action adventure and a fun ride.