Hiya!
I'm in the "meh" camp. I loved playing Ravenloft when it first came out. It was different, that's what I remember. Different setting with some different rules and the 'visuals' were a nice change (we pictured stuff like it was...hmmm...like the movies Sleepy Hollow or Red Riding Hood (2011)). Was it "horror"? Nope. Were we 'scared'? Not really. Why? Well, it's hard to be 'terrified' of ghouls, ghosts and a vampire when your characters have already been through being slowly dissolved in acid, eaten alive by giant rats, dismembered limb from limb by an ogre, have have had their body literally explode from a lightning bolt of pure magical electricity. "oooo....spooky!....a vampire in his creeeeeppyyy-cassstttleeee....oooohhhhhooooo....!".
And that is why Ravenloft is good for a "one off" or a "mini-campaign". A nice jaunt into a different setting with some different rules. But, seriously, anyone who thinks Ravenloft suddenly becomes "more horrifying" than any normal adventurers Tuesday night just because 'it's Ravenloft' is deluding themselves. IMHO, a better fit for a "Ravenloft" game would be to use the Basic Role-Playing System from Chaosium. It's got all you would need to really bring in a "horror-fantasy" feeling (locational hp's, low hps', magic-is-dangerous-and-insanity-inducing, actual SANity rules, etc). By using D&D, everyone at the table is going into it with a D&D mindset (re; "We are different than everyone else. We are tougher. We've been there, done that, and things that make a normal person instantly wet themselves bring nothing to us but a slight smirk of impending violence...or, 'fun', as we call it").
*shrug*
^_^
Paul L. Ming