I think Teresa made a very good point on the Da Vinci Code, in that it was controversial, as it offended many orthodox believers' views, which of course got others to look at the thing to see what all the fuss was about, and this became something of a self-perpetuating cycle (at least for a time). As his more recent books are still riding on that wave, plus a certain amount of connection to related themes, I think that's going to also play into how well they do. As for your response to the book above... I can't tell for certain, not knowing how you express yourself on such things, but "OK" doesn't exactly sound like a ringing endorsement.
On the first bit of this, I was basing my response on your statements, unqualified in the post:
and
The way that is phrased, it doesn't sound so much like opinion as a form of obiter dicta, while the "I don't accept the statement from some" certainly makes it sound as if you are saying they are either in denial or lying outright when they say such. I'm not saying you intended to offend anyone with it, and I apologize if my own response was offensive to you... but I don't see how those statements could be read any other way.
On the second... you'll note that, considering the effect of "fans", I immediately qualified that. I'd much, much prefer moderate sales and a low profile. The more widely read you are (especially if anything you write is genre writing), the more likely you are to attract a fair number of obnoxious types who think it is their right to make demands of you as a writer (and, not infrequently, as a person). Even given the unlikeliness of this being a possibility with me... no, thanks, I'll pass....
(And for those who can't understand this view, I urge them to look up Ellison's essay, "Xenogenesis", which can be found in the first volume of his Edgeworks series. There, he not only gives his own experiences with the type, but those of many another writer in the sff field. And then we have the experiences of such as Stephen King concerning fans and their incursion on his home and family, as well....)
As for whether or not Brown thinks his is good prose, that's another matter -- most likely he does. He wouldn't be the first mediocre (or even bad) writer to think so. And, of course, the fact of present sales gives a specious appearance of soundness to such a view... but I'm afraid that's all it is: a specious appearance.
This is not to knock Brown particularly; if he is writing to the best of his ability, and he is able to sell millions of copies, the best of luck to him. When it comes to that, if a writer is being conscientious at their job, then that's all anyone can reasonably ask of them. If they catch the public's attention and do well, fine. If their writing is poor I'm unlikely to be among their readers (though it's not impossible; I also have my likes among the poorer writers), but, as I said, this means absolutely nothing as far as the actual quality of their writing is concerned. That is something that, despite many claims to the contrary these days, really does have a much more objective basis than any one person's opinion or even the opinion of a single group. It is a difficult thing to define, and would actually take a reasonably lengthy essay to even begin to address the topic properly, but it doesn't come down to something as simple either as what a group of critics (whether we're talking reviews or more in-depth literary criticism) or the best-seller lists have to say, good or ill.
I take it you're referring to the Ennis/Dillon comics/graphic novel series? I think that has something to do with the difference in media, Lobo. Whatever the merits or faults of such, these are still not viewed in the same light as straight text novels (or, for that matter, short stories), any more than screenplays -- whether for television or movies -- are. Overall, I'd say that is sound judgment; but in any event, they are quite different media, with different strengths and weaknesses, and require different critical approaches (at least to a large degree).
I've not read Mein Kampf in the original German, nor even complete in an English translation (though I did read portions of it over 30 years ago, as it was in our school library), but from what I did read... no, quality literature is something I would definitely say it was not....