I've played in Ravenloft a few times. I like the setting well enough, but we had a less-than-stellar DM running it. Luckily for my players (who hate Ravenloft with a passion) I don't use it very often. I'm too fond of making up my own cosmology for the worlds I create to buy into TSR's big marketing ploy to make everything interconnect.

"Who would win if Raistlin and Elminster got into a fight?" Who cares, they don't exist. Just concern yourself with how quickly the undead God-King Alloka'ir will rain death on your heads should he ever cross paths with you again... I've got plenty of wonderful and downright horrific things to pit my players against without using pre-packaged worlds.