The only commentary that I have watched thus far is the pilot. But I watched the BTS videos recently, and there was one that touched on the fact that Siler was unexpectedly a big hit among fans. He was popular because he was effectively the everyman character, giving representation to the working man. A lot of fans saw themselves in Siler and fell in love with the character.

An exchange I really liked recently:

S01E17 "Solitudes"

DAVIS: We've almost replaced all the super conductive interface elements, sir. The old ones all melted. It's going to take some time to load test them, though.
HAMMOND: Just tell me the minute we can send a probe through.
SILER: That'll be 24 hours, General, minimum.
TEAL'C: Captain Carter and Colonel O'Neill do not have that long.
HAMMOND: I'll give you half that.
SILER: No, sir, it doesn't work that way. 24 hours is the best I can do.
HAMMOND: [PAUSE] Then you'd better get back to it.