Certain amounts yes. But a delay in release causes more and more hype. Think about George R.R. Martin, there was an absurd delay between books 3 and 4, and it led to a generally poor reception of book 4 - I don't see how book 5 can have anything other than the same reception at this point.
Now, you point out that it was really all just one book, so therefore you can realistically expect part 2 to be just as good. I don't think you can expect that at all. You can hope--as I certainly do--that it will be as good, but over-hyping expectations generally leads to disappointment. By your same argument, we can say that we should expect book 2 to be worse, because the middle of a high proportion of fantasy novels are terribly slow, and are used exclusively for set-up. Pat is a good guy, and a good writer, so I don't think this will happen. However, people need to step back and breathe a bit rather than expect the greatest fantasy novel ever written over the history of time, and in all parallel universes (cause that is what people are starting to do now).
I would kill to be published like Pat, but I don't envy the hype fans are pumping into his book 2. Personally, I will be satisfied with an enjoyable novel that can be slightly less awesome than book 1, and I feel that is a realistic hope and expectation. It also allows me to be blown away in the event that he goes to a whole 'nother level of awesome.