I enjoyed 'The Da Vinci Code' at the time, although it isn't terrific writing. It kept me gripped on a long, boring train journey, anyhow. One of my favourite novels of all time is 'Wuthering Heights' which is, arguably, incredibly self indulgent and wordy. And Jane Austen - a fantastically clever and skillful writer - leaves me yawning. So, yes, I do differentiate to a certain extent. (Although I draw the line at Amis. Don't like his writing personally and think he is pretty darn overrated generally ).
I think it's safe to say that most pop fiction - the whole chicklit genre for example - is quite frowned upon by people who consider themselves serious readers. I don't write it off so easily, though. I'm a Lit graduate, have read most of the classics, enjoy 'literature, dahling'...but I also quite enjoy a good old Jackie Collins or Barbara Taylor Bradford on a beach holiday, and I think some of those pulp fiction American writers - Elmore Leonard, Laurence Shames et al- are utterly brilliant.
Sorry for the waffle. It's nice to talk books :-)