Yes, it is fairly gruesome. Perhaps more blood and violence than you would typically find in a Poe story, but as the newspaper editor insisted, that's what the people want. That's likely true, but what I like about Edgar Allan Poe's writing is the intelligence, prose and soulfulness that would be hiding amongst all the murderers and dead bodies. Most stories can be deduced to be about something entirely other than just the crimes. That wasn't really the case here, but that's hardly the fault of the film as they are different mediums.
They might not have gotten the underlying meaning, but they did the get the true nature of Poe accurate. His gloomy, brooding obsession with death, women and alcohol. I've always been convinced of John Cusack's aptitude for this role, and contrary to popular belief, he was very good. He was more subdued than most people were probably expecting. No action stunts and no over-the-top dramatics, he just showed how words and his propensity for gin would haunt him. He delivered only a few quick lines of wit, and I'm assuming that was the issue people had. From all that I have read from people wanting Robert Downey, Jr in this role, I'm assuming they have confused the fictional character of Sherlock Holmes with the real-life writer of Poe. All that I can say to that is thank God Cusack never got confused.
Sir Arthur Conan Doyle has credited Poe as inspiration for the creation of his famous detective. I'm afraid the filmmakers have tried to re-pay the favour and took some action cues from the recent movies. Watching bullets fly through the air really takes away from the few things they did so well.
"The Raven" is a good watch for Poe fans with references to many of his stories and poems and they found great moments to include some of his illustrious and lasting lines. Although I would have liked it more if the movie was just a dramatic recreation of his famous poem, at least Cusack did offer a reading of The Raven which probably mirrored that of Poe himself.