"Boring" is a relative concept. By a western standard, most Soviet films are incredibly boring, with their glacial pace and over-reliance on exposition and mopey acting, but in actual fact a lot of 'em are really really good if you have the patience to crack the artistic code they're built atop. Likewise, if you watch, say, "Dick Tracy vs. Crime Incorporated," it's hyper-exciting - an action sequence literally every seven minutes through its 90 minute run - but that can't really distract one from the fact that it is a terribly, terribly boring movie.
In the case of B5, most of the people I've met who say its boring *seem* to mean "I don't have a framework by which to understand this, so it's not holding my interest." I don't know how old some of you are, but back in the mid-90s there actually were a sizeable number of people who quite literally couldn't comprehend of SF that wasn't Trek. And a lot of people don't like SF to begin with. And let's face it - from day one, the B5 method of storytelling has made considerably greater demands on its audience - and far greater assumptions about their intelligence - than Trek or SeaQuest or either Galactica ever did.
So in my experience, it's not so much boredom as it is sense of being overwhelmed. "You mean I have to watch thirty six hours of this to even understand what's going on? Nuts to that!"
