Well, in my case at least, I was very mixed about the film when I first saw it, and that was because I imposed my own expectations on the film. I had my own idea of what the film should've been like and how it should've ended. However, since its release, I have seen the film two more times, and it has grown on me considerably. I now think that TDKR is just as good as the first two, and it concludes the trilogy in a very satisfying way.
The problem is, I went into TDK completely clean - I had only seen the trailers, and that was it. I wasn't on message boards, hunting for spoilers or speculating about the plot for months. So when I saw the film, I felt like I got hit by a ton of bricks (in a good way, of course!). With TDKR, my anticipation was through the roof and I was following the pre-release speculation and chatter religiously. So therefore, when I saw the film, my initial reaction was much different than with TDK.
Once you accept the film for what it is, you understand the story it's trying to tell. You realize that TDKR does this trilogy justice, and that is all that matters. In the end, this is Nolan's vision of Bruce Wayne's arc, not mine.