This film is excellent, that's the only way I can explain it honestly. The monster action was amazing, and Duncan's 'dragon' form was equally cool looking, as was when we see him transform into it. The creatures were designed well and were pretty cool, just varied enough to make the name Kaiju fitting. Belloc is actually an intresting character and an awesome kaiju design, though his ability to 'change his face' is wierd, but makes sense by what he was, and he was strong enough to justify calling him King of the Kaiju.
The characters were excellent. Duncan was pretty good himself, nice amount of developement to care for the guy. While the other characters didn't get the same degree of developement, they got enough to care for them. So its fun to watch.
Another nice trait is the film doesn't try to copy the comics, it has some common traits, but overall, it forges its own path and makes a unique story. I think this made it much more enjoyible than if they tried to retell the comic story.
I really liked this film and REALLY hope a series is spun off of it. I know I'd watch it.