Will it be crap? No, I don't think so. I mean, not when you compare it to, say, any Transformers movie, or to yet another Fast & Furious sequel, or to G.I. Joe.
But I have a feeling it'll disappoint a lot of people. Mostly people who've hyped themselves into a frenzy, though. But hey, the same thing happens with iPhone releases.
I too think that, while The Dark Knight was entertaining, it wasn't quite the ZOMGWTFBBQBESTESTMOVIEEVAR!!!111!!! that a lot of people made it out to be. I think much of that had to do with (a) Heath Ledger's performance as the Joker, and (b) Heath Ledger's untimely death following hot on the heels of that film. I also agree with folks who've said that the Dent storyline seemed...too compacted. That's kind of how I felt about the whole film. Was it enjoyable? Yeah. But for all it's running time (wasn't it, like, 2.5 hrs?) it still felt kind of rushed in some ways. It didn't flow the way the first one did.
One may not particularly like the story or portrayals in the first film, but structurally, I felt it just flowed better than the second one. The second one felt less focused and far "busier." This, of course, is the curse of comic book franchise films. The first film is always tightly focused and tells a coherent story. The second one goes "bigger" and while remaining entertaining, feels....like it's getting a little crowded. The third one goes "even biggerer" and usually falls apart under its own weight.
And while everyone may say "BUTNOLANISTEHBESTESTDIRECTOREVAR!!!!111!!", frankly, I think he's good, but he's oversold by his fans. I've enjoyed some of his films. And I respect that he doesn't just make the same old schlock. But people who enjoy his films treat them as if they're the second coming and they just aren't.
I heard people RAVE about Memento for ages before I watched it. Then I watched it and, while it was interesting, it was...just a backwards story. Neat concept and well executed, but...um....that's it. "But DUDE! It's BACKWARDS!!!" Yeah, I got that part. Neat. Is that it, then?
Ultimately, I think Nolan's films work best when people don't know much about them going in and haven't heard much. I heard WAY too much about Memento before I saw it, and thought "What a piece of crap!" (Which really was me just saying "Well, THAT didn't live up to all the hype...") I went into Inception not having seen a single trailer, but having heard about the concept of the film VERY briefly, and thought "Cool film! I liked it."
The Batman films are doubly difficult because they're a franchise, so you already have preconceived notions and expectations. As a result, I think it's doubly hard to avoid the inevitable hype.