What I think I like most about a good meta-text is how it can work with anything, so long as you have the knowledge of the genre. In a fashion, it rewards people who know a particular canon, and punishes those who don't, but I don't particularly see that as a problem. I'm fine with literature that alienates one audience to work with another--the idea that everyone has to be able to get a piece of work has never really struck me as an interesting concept, and I can't really figure out why anyone would peruse it. Of course, when I talk about a meta text, however, I don't just mean taking an existing novel and, I don't know, jamming zombies or vampires in it, such as the current crazy in literature seems to be. The Jane Austin novel with zombies was interesting as a concept, but I swear, the other week I saw a novel in which Mr. Darcy was a vampire, and writing angst filled letters of dark love to the general public--but neither are, at least to how I view it, a piece of meta-fiction. They're more what I would call collages, remixes, and a shameless grab for cash.
No, to me, a meta-text takes an original story, and wraps it around a genre, or an author's body of work, and attempts to marry the original narrative to the second. If it's good, it will function on two levels: the first as an individual piece of fiction, hitting its required notes, plot points, tensions, and so forth. But secondly, it will use those notes, plots, tensions and everything else, to ensure that the conversation about the author's work is taking place, and that its resolution manages to tie into a climax either in the opinion of the author vs the state or genre he/she is writing about, the the end of the movement or work. It can end in other ways, of course, but for myself personally, I like when the two can be mixed together in their climax, and make them work in some kind of geek content pleasure overload.