I won't argue whether this is Victorian literature or not. It fits the bill.
This novella is filled with all the things that make a creepy old story all that it should be. It takes place on a lonely moor. There's a creepy old manor house. You've got your ancient family curse, and a black devil hound roaming the moorlands at night. Mysterious residents people the place, some odd, some quirky, some dangerous. There are ancient ruins, bogs, and that foggy atmosphere that makes this a wonderful piece of fiction.
Oh yeah, Sherlock Holmes is in there somewhere as well. But he's not the central character. The hound holds that spot. Holmes is merely the one who comes along and figures this whole thing out. That's not too different from other Sherlock Holmes stories. He's told a tale that has nothing to do with him and it takes up most of the story. Then he comes along and puts two and two together.
Here we have Watson, mainly, taking control of the new baronet who's been brought home from the wilds of Canada to take over the estate. Shades of Downton Abbey, but without the beautiful daughters all looking for a husband. Watson shows him the ropes and keeps him off the moor.
Stay off the moor at night, my good baronet. That is Watson's job - to keep Sir Henry, the new heir, off the moor at night. And if he fails at it, the vicious hound will eat him alive!
The British always find their missing sons in Canada. Sometimes in Australia. Never America, mind you. No, they remain loyal to the crown. But the way they described Sir Henry you would think he was a lumberjack, and would expect him to show up with a beard and red flannel. But don't worry, he still retains enough of his Baskerville upbringing to remember all his good graces. Upon returning to his bleak homeland on the moors, he jumps right in like he's always been there.
There are a few subplots to make the story interesting. But for the most part it's a mystery, and you don't know the truth until the end. Doyle was a master of this. Sometimes he lays out the clues so you can figure it out, but sometimes he doesn't. In this case, it's likely you could guess but unlikely you would know based on what we the readers were told.
This book is the quintessential horror story of ancient curses, old manor houses, and scary, bleak moors. It's the archetype that others are held up to. It is the example that others follow. What it lacks in supernatural horror, it makes up in imagery.
Sure, it's a period piece. But the subject matter probably gave it that feel even when it was first released. At the turn of the 20th century, a story that harkens back to medieval times with old curses and ancient manor houses most likely had an "old" feel to it. So in that respect it's not that different today than when it was written.
I would recommend reading this around Halloween. Get a glass of wine, sit in front of a fire on a dark, foggy night, with the only sound the crackling of wood. And perhaps, far in the distance, the faint howling of a grotesque, gigantic hound.