these vampires will attack any town you go near or enter
an example is that i had an attack while i was in whiterun, the master vampires managed to rip the villagers to shreds so i reloaded. A vampire attack happened again, this time only one master vampire i managed to kill him off with no casualties. i went outside the gates of whiterun to the stables only to find two death hounds taking out the npc's there as if they were nothing, my horse was thrown into the air and killed instantly. i reloaded multiple times trying to save all the npcs but every single time they managed to die, i then decided to reload to before i travelled to whiterun so that the attacks never happened.
I'm paranoid because i know that the vampires can kill npc's without you being aware of it going on, whether the vampires massacre the npc's on the other side of town or the mysterious traveller sneaking into house without you ever knowing they were there. i dont feel safe entering any town now even if i dont see an attack because i know that there is a massacre probably happening on the other side of town. i have played atleast 20 hours plus since buying this dlc and i will have to reload it to before then because i dont feel comfortable knowing that npc's are dead, they should only die if i kill them myself.
the people which think these are just as bad as dragon raids need to think harder, dragons attack towns on their own. they have their own battle music and are easy to spot, they only ever focus on one person and most of the time its the player, if npc's die then you can reload. lower the difficulty and get rid of the dragon with ease.
now with vampire attacks they come in a variety of forms. master vampire and the weaker vampires attacks in groups and can eliminate npc's with a single blow most of the time. the mysterious traveller killing off npc's in their houses while you are busy killing off the other vampires, death hounds are unfairly fast and over power npc's very easily.
the people which think this is a good feature are wrong, you may think its fun now but do you really want to baby sit every npc in every town, stable, camp you visit for the rest of the bloody game? it WILL become an annoyance inevitably. in time every single npc will be dead. no more shopping or collecting quests. bethesda said that the player controls their own experience. if you want danger go to a cave, ruins or fight dragons and giants. if you want some time to relax, store your gear. go to town and speak with the npc's. this new feature has removed this and turned the whole game into a war zone, it feels more post apocalyptic than the fallout games, and its more unforgiving than dark souls.
I'm all for vampire attacks just not in towns and cities, let them attack me in the wilderness as long as npc's dont get harmed. bethesda get your [censored] together.