Never read the comic, I do however assume that a lot of what went into the comic came across to the movie. The various creatures in the movie are done very well with attention paid to their mannerisms. This contributes to making them more believable.
As for Hellboy himself, he has an interest in Liz the girl that catches fire. This results in more than just an action movie where Hellboy goes up against other creatures of the night to protect us. The end result is quite a good movie that still has a lot of action as well as some decent characters along with a good story.
This film starts at the end of the second World war, we have the professor leading allied forces to a castle in Scotland where we come across two Nazis opening up a portal to the other side. While the portal is open a young creature (Hellboy) is brought across. The professor takes charge of Hellboy's well being, fast forward a number of years and the ageing professor is now head of Bureau of Paranormal research.
As the professor has failing health he recruits a young FBI agent to partner up with Hellboy. The Bureau also keep various creatures of the night in check. Their main threat however will come from the two Nazis that managed to get away so many years earlier. They are still interested in opening up a portal and destroying Earth.
hellboy I was kinda good...not great but fairly entertaining.
Hellboy II...not so much
.......but sequels rarely are.
Agree, a bit disappointing especially the sequel.