It was pretty good. The movie was definitely a summer action type of flick; the plot existed but was glanced over in a cursory manner, but that was ok. It had a lot of atmosphere, surprisingly decent acting (I expect bad acting from my action movies), and was pretty exciting.
So the movie is about a world - our world - where dragons exist. However, they didnt' always. In the modern day, an urban tunneling expedition in London (digging sewers? subways? I forget, it doesn't matter anyways) breaks through into an underground cavern. The son of one of the miners goes in to explore, and comes out screaming, chased by (guess) El Dragono.
Anyways, twenty-odd years later, the boy is now living in the ruins of a castle, which has become a small encampment or village of sorts, with him as the leader. Dragons have taken over the world, more or less, almost everyone's dead, and they're basically just waiting to die. They've given up on life, essentially, but fight to stay alive anyways. Just in case, y'know.
Well, the just in case happens when the Americans roll into town with a few tanks, and *gasp* a helicopter. It turns out these wily yanks have figured out how to kill dragons, by using a combination of suicide and giant crossbows.
The americans demonstrate by committing suicide (there be sarcasm in them thar hills) and killing a dragon. They then recruit some of the tired old brits to try to hunt down the male dragon, since apparently one male dragon is responsible for populating the entire species.
Then they all die except for two americans, so they go back, and the two americans and the leader of the brits go and kill the male.
Ok, so, did I mention that the plot is somewhat lacking? That's ok, because the movie more than makes up for it in other ways. It's exciting, it's a modern-day tale of dragon slaying, and there are some very amusing references as well. I love how the modern world has been practically transported back into medieval times; the visual of quinn (the british leader, if I recall his name correctly) galloping around on his horse, a dark cloak billowing out behind him, a rifle jutting up over his shoulder like the hilt of a sword... c'mon, that's pretty cool. Taking on dragons with helicopters and machine guns and battle axes, there's some real appeal there.
The dialogue was ok - not great, but definitely much better than standard action fare, and as I mentioned, surprisingly well acted. It was really more than just an action movie, and was pretty good.
The ending was disappointing - the dragon died way too easily - but that's ok. It also doesn't explain what happened to the thousands of female dragons, either, but that's ok too.
Overall, it was fun, and worth seeing. You need to be into that sort of thing to truly appreciate it, but if you are, you'll have a lot of fun.