Part of the reason is Joss Whedon, the man behind Dr. Horrible’s Sing-Along Blog. Whedon — of Buffy, Firefly and Serenity fame — is known for snappy dialogue, engaging stories and a keen talent for creating fan buzz. Last week he released Dr. Horrible with little fanfare, posting three fifteen-minute episodes throughout the week. You could view them for free on the Dr. Horrible site, but only through last Sunday.

Now they’re $1.99 each on iTunes. And worth every penny.

There’s nothing new to this comic tale of a nascent super-villain trying to make it into the big leagues, but when that story is told with Whedon’s flair for dialogue, a half-dozen musical numbers and the comedy genius of Neil Patrick Harris in the starring role, it’s gold. Whedon regular Nathan Filion plays Captain Hammer — the doctor’s arch-nemesis — with oblivious, scene-eating verve and the entire production manages to be slick and humble at the same time.

That might be the ultimate appeal of Dr. Horrible. The countless home-made video blogs and shorts posted on Youtube and the like create an aura of low expectations for web films, making it easy for Whedon and crew to surpass the perceived potential at every step. The actors are better than the script, the script is better than the plot and the plot is good enough to generate some pathos and interest. Most of the laughs come from obvious slapstick or surprise — the head of the League of Evil is a villain called Bad Horse (the Thoroughbred of the Apocalypse), silently played by an actual horse in the show’s final scene — but they work.

Experience has trained all of us to know in our bones that 99% of online entertainment is pure crap. Maybe the real lesson in Dr. Horrible is that a skilled storyteller and some out-of-work production pros can turn those lowered expectations into honest-to-goodness blockbuster fun.

The show, which runs about an hour and a quarter, has the same visceral, hyper-real feel of The Wire. GK is based on a book by Evan Wright, who was embedded with the Marines as a reporter for Rolling Stone. Its executive producers include David Simon and Ed Burns (yes, from The Wire), who also do a fair share of the writing.

The show depicts the confusion, tension, bad decision-making, dearth of suitable equipment and the general chaos of the war. It doesn’t shy away from making out some of these Marines to be assholes. The repartee between them is thoroughly uncompromising and often very funny (especially from the mouth of fast-talking Cpl. Josh Ray Person [James Ransome]).

The calm in the center of the storm — the moral center of the huge ensemble cast — is Sgt. Brad Colbert (Alexander Skarsgard), a lanky natural leader who knows how to share a laugh with his men but never forgets for a second that war is a very serious business. And he doesn’t let his troops forget it either, although a lot of the grunts seem to view the whole process as fun-and-games.

It was a good choice, I think, for the producers to have a main character be a particularly noble example of a U.S. fighting man.

I wouldn’t have expected Iraq War battle scenes to amount to much, mostly because we were led to believe on the homefront that the invasion was something of a walkover. That may be essentially accurate, especially when compared to more hotly contested wars, but GK is a stark reminder that these troops definitely found themselves in harm’s way.

And although the firefights aren’t as crazy and chaotic as, say, Saving Private Ryan or Platoon, they still show situations that can put a shudder into you while sitting on the living-room couch.