I think the worst reaction was on (where else?) Newsarama - following an interview in which Morrison said that Final Crisis contains some unexplained plot details because he wanted the reader to use their imagination, among the first few comments came an outraged rant that it was the equivalent of writing "F You" on a blank piece of paper.
Ergo, it is presumed that the kind of comic fans which frequent Newsarama don't like to be told to use their imaginations.