I agree that perhaps Henry dismisses novels too quickly as 100% entertainment, and doesn't see their real-life application. It's hard to tell – the General is his father, after all, so maybe Henry doesn't want to tell Catherine that his father is strict, hard to live with, etc. He might privately see the application, but in the public context of NA he doesn't share his insights with Catherine. All speculation on my part! :)

Back to the book – I think if JA is using NA to show us different types of reading styles, Henry is meant to be another example of misreading novels. Catherine may take novels too seriously; Henry may not take them seriously enough. Eleanor's comments on reading history in ch. 14 ("I ... am very well contented to take the false with the true ..." etc.) suggest that of all the readers in NA, she might best understand the balance of fantasy and reality in novels.