Northanger Abbey is the first novel finished by Jane Austen. I read it in about 24 hours in Florida. It's quite short (particularly compared to the expansive Emma) and extremely amusing. I think I enjoyed it equally to Pride and Prejudice and more than Sense and Sensibility.
Like her other novels, it's a love story wrought with the intrigues of England and is critical of the society of the time. Unlike her others it lacks subtlety. It is fantastically sarcastic. The overuse of positive, flattering adjectives borders on cruel. Most of the characters are atrocious, empty-headed, superficial assholes—disguised as very good friends. They are just horrible. On the other side, there are three 'heroes' if you will, who are nearly beyond reprimand, flawless.
The novel (as her first attempt) isn't entirely without fault. The flowery language which mocks the speech patterns of the time is sort of hard to read in parts. Not only is the dialogue in this pattern, but the author uses it herself and addresses the reader directly. There is also some imbalance between the plot and the tangents of social commentary, particularly regarding horror novels and the importance of dress, art, music and theater.
Nonetheless, the heroine, Catherine, is quite likable (despite her excessive kindness and goodwill) and her ignorance is endearing. If the book was longer than 211 pages I think I'd find her tiresome, but it doesn't so she's perfect.
Basically, I highly recommend this book. It has a distinctly different voice from other Austen novels and is much more humorous and blatant in its judgment of English society and women in general.