Northanger Abbey is a prime example of how tastes in reading have changed. This book has a lot of description in it and has a very slow pace. In fact, cut out all the tours and the long descriptions of the locations and the book will be half its length. This means readers are probably skimming a lot, unless you're weird like me and believe you were born in the wrong century. I like the descriptions and the old-fashioned way of speaking because I love the time period. However, in this case, they weren't things the author put in in addition to the story. It is how they spoke at that time. Authenticity guaranteed.
The romance in the story is completely different from modern ones. There was no real spark, no "take me" physical attraction, no chemistry between the heroine and her suitors. No sex. Sex isn't even hinted. I'd be curious to know whether that is how courting was supposed to be during that time or if it was a "Oh, no. She can't have *feelings* like that for him. No one will ever publish the book if she did." Maybe I'm slow when it comes to picking up the mutual-attraction thing, but I didn't see it in Northanger Abbey, other than through Catherine's insistent search for Mr. Tilney after she meets him. That got on my nerves after a while. It was a dance. He probably left. Why obsess over the guy?
Even if the book were modernized, so the characters had chemistry, so a simple kiss resulted in a near orgasm, and the long descriptions removed to the basics...I'm not sure the book would have enough to survive as a modern novel. The only real intrigue is in Catherine's mind and it's short-lived. And the novel, most likely, would read like a teenage drama without the paranormal elements.
I think it's a good book. But modern readers need to consider that the book is not the fast-paced googly-eyed romance of modern times. It's a slow story, told as a parody on society. And, as I don't live in that time period, may never fully realize what it parodies. I normally don't read parodies as a rule either.