I won't say much beyond nodding hello to my seatmate which sometimes starts a conversation although it's not really intended to. I'm always game if someone wants to talk, though. In my experience, most people inclined to talking usually chatter for 15 minutes and then go back to napping/eating/reading/watching a movie/working or whatever.

I find it pleasant in small doses, but I wouldn't relish being seated next to someone who felt compelled to talk for the entire flight... that has never happened to me, though.