I just finished IM
To be honest it took me a while to get into it because the characters were so empty and hateful. But as it went on it was like a celebration of the cold and shallowness people can exhibit when they have little else going for them other than their looks.
The ending is by far one of the best twists I've ever read and I went away from the book with a change of heart and an even greater respect for Chuck and his writings.
I still like Haunted the best though. 
Invisible Monsters is in my humble non-professional opinion his best book. And then comes Haunted. I always like the twists in his novels, maybe that's why I only liked Tell-All after the half.
i also loved IM; it's tied for first with Choke.
in Haunted my fav part was the lady that worked in the police station; her whole bit was great. the rest wasn't so engaging for me, but i did enjoy it enough to read it through.
I don't know if IM is my favourite, but it's definitely up there. I thought there were some very clever scenes - I should definitely re-read it.
I also love those with a twist, something that keeps me guessing, and where you realise halfway through that you're only looking at the surface layer.
I liked IM, too. I wasn't sure how I'd feel about the ending, but I ending up really liking the book.
My favourite by a long shot. From the individual scenes, and brutal one-liners to the topic of Vanity, and how our society determines value.
"I hope you realise the story you're telling yourself, because every day you die for it."
As a whole I wasn't a huge fan of IM, but there were a couple chapters that were extremely well executed (I wish I would have marked them). The Space Needle chapter was really good, so were a couple of the family incidents. The ending I wasn't very impressed with. It seemed over the top for the sake of being over the top. I kind of felt the same way about Lullaby's ending. It just seemed like Chuck felt obligated to end on a disgustingly violent note. It didn't bother me too much with IM, b/c I wasn't a huge fan of the book anyway (and that's how it started), but with Lullaby I felt it really detracted from the quality of the story.
"[B]eing good is a fearful occupation; men strain at it and sometimes break in two." - Ray Bradbury
i just finished invisible monsters and it was one of the best of his books ive read so far, the multiple twists and demented ideals of the characters are amazing
yeah, the 'poems' weren't too good. Chucky P. should probably stick with the prose. but good on him for having a go, although, i'm not sure what they added to the novel. i never liked Haunted all that much either. same with you, Mirka, after the first couple of poems i just couldn't go there. the present story was weak and some of the shorts weren't too great either. not his best work.
IM on the other hand was a fantastic read. right up there with fight club--gasp!--and survivor for me.
I laughed the most during Survivor, but IM felt the most....complete to me, for some reason.
It's almost like it had a heart to it, and I felt kind of mushy at the end with the "I love Brandy Alexander" part. :3
It sucked me in right away, and it's still my favorite book by Chuck. I didn't like Haunted much. I couldn't read the poems in it.