I have to say I was disappointed with Hellboy II, as there were a number of flaws with the movie:
1) The plot. The initial set-up of the story worked well, but then everything stopped and we were shown an hour of the BRPD dicking about at HQ, which had nothing to do with the story; then in the last five minutes Del Toro must have thought 'oh crap, I better finish the story now' which resulted in a very quick ending with very little gravitas.
2) There was no challenge for the characters. Everything was too easy for them. In an epic adventure, such as the trailer depicted, you expect the characters to encounter problems which they must solve. The slapdash ending had none of this, I will now re-create the ending:
"Oh look at this map...he has gone to Ireland."
*cut to Ireland*
"We are in Ireland, oh look a goblin! Do you know where the evil guy is?"
"Yes and I will take you to him, but first I must take you to see an awesomely designed creature for a pointless twenty seconds of dialogue."
*cut to evil elf and Hellboy fighting for ten minutes*
"...she is dead. Let's destroy the golden army now."
"I'm preggers."
THE END.
3) The characters and the script was poor. (Maybe Del Toro should leave the English dialogue to someone who can speak the language, as that might have added some depth to the flimsy script?) I will present you with a couple of examples:
Firstly, when Abe fell in love with the Princess instantly:
"Let me touch your hand.."
"OK."
*they touch*
"...I think I love you."
This was TOTALLY out of character for Abe, he is supposed to be logical, rational and intelligent...not desperate.
Secondly, when Krauss tried to stop them taking the plane:
"Do you have authorisation to take the plane?!"
"Hellboy is dying."
"...I once had a wife who died. Ah, what the hell...let's take the plane."
It was such a sudden, fickle change of direction for such a stubborn, logical character that it didn't make any sense, and just seemed like poor writing.
4) The huge battles which were just excuses to show off Del Toro's wacky creatures. An example of this is the ten-minute battle with the forest elemental, which starts off by having the evil dude throw a bean into the drain...
The troll market irritated me, as it just seemed to be another excuse to show off designs.
The CGI was good, but that should only be a small part of a movie...it is the acting, plot and script with bring the life to a film. I think the 'bad acting' was more likely down to a bad script.