(Remagoen took the time to go over this in great detail for me. Thanks, buddy.)
In other words, I have a much different interpretation of Colonel Sumner than any SGA author I've ever read things by. Which I usually don't mind - I've read absolutely stunning stories that cast Sumner as the block-headed bully. But, really, I think he deserves better treatment than that.
I'd read of Sumner in stories before seeing the first two episodes of SGA, but the fact that I am fond of Robert Patrick's role as Doggett in X-Files led me to pay more attention to his actions than I would have. I knew the fandom's view of the man, so I was interested enough to pay him close attention.
Though common perception casts him as humorless, he made a few one liners that show differently. (Granted, I can't remember any specifically, which might be because my memory tends to have holes like swiss cheese). I noted the look on his face as he stared at the submerged Atlantis - as awed as any of the other three looking out the window.
I think a major reason people tend not to like him is the comment he made about Sheppard, coupled with his military bearing and apparent lack of personality. What he says is something along the lines of, "I don't like soldiers that don't follow orders." Now, the audience knows Sheppard had a good reason for not following those orders. It's a personality trait of his that has saved the day many times, giving quite a few episodes happier endings than they may have had. Colonel Sumner, however, has a good point. Think about it; If you are leading people in a chaotic situation, you can't explain everything to everyone. You may have vital information that you don't have time to explain, and if your officers act ignorantly and do what they think is the best option without trusting you, then everything can go straight to the deeper levels of Hell. Sumner's not saying Sheppard's a crappy soldier, or that he hates his guts or anything - he's just cautious. And he's right to be.
And Sumner's last scene. Oh, that last scene. He knew he was being interrogated. I could hear the horror in his voice as he learned what the Wraith are, what they do. Even the Wraith queen admits that he's very strong willed, and he put it to use as he didn't tell her anything about Earth even as she was sucking his life out through his chest.
I'm not saying you have to like him. I'm not saying he's a shining example of good will and cheer, or that he wouldn't have made mistakes had he continued as the military leader of Atlantis. I just ask you to try to look at him a little more honestly, okay?