I'm going to go old-school and say "I like my darned level drain." Heck, I wish they would bring the AD&D level drain back. As a player, and a DM, nothing scare ME, not my character, ME, more when playing the game than rumors of a wraith or vampire being in the location of my next adventure. Kind of like a Jenga pull in Dread, that risk of doing the wrong thing and having an undead smack you for level loss (that could be restored, with spells) was just mean, and ultimately led to some great stories where our groups went through all sorts of contortions to avoid the undead beastie and trying to douse it with holy water/ bury it in sunlight / release it from its curse / whatever, because NO ONE wanted to face the damn thing in direct combat.
That was just my experience with it. It may have been "unfun", but it was because of that why we actively sought to avoid it.