The Masterpiece Theatre website now has a forum to discuss all the shows here. Should be interesting to read the opinions of NA after it airs on Sunday evening.

There are a number of interviews with the writer Andrew Davies on the website too and he mentions the Northanger Abbey adaptation a couple of times.  

There was a nice preview article about NA here:

"Northanger Abbey airs next week, with gothic novel-addicted Catherine Morland the perfect complement to Persuasion's internalized Anne. Northanger is Austen's first work, and features a 17-year-old protagonist suffering the effects of an overactive imagination. The PBS ending is truncated, the character of General Tilney given short shrift (as is the estate of the title) but actors Felicity Jones and JJ Feild are wonderful in the leads, as is Carey Mulligan as feckless flirt Isabella Thorpe. "