I love Jack's bitching - "That pup tent smells like cat piss or worse," "Ya know, I'm commutin' 4 hours a day...," "Ya won't get much sleep, I can tell ya that," "Aguirre got all over my case like I was s'posed to control the weather," "Beats workin' for my old man - can't please my old man no way," "Why powder your nose just to go home and go to bed?" "No more beans!"
As you guys mentioned, I love it all the more when he says "I complain too much" because it's just about the essence of him (in not such a negative way, of course), and he sums it up himself in that one little phrase.