Note about the opening. It starts right from where the third book left off. With this I think Tolkien wanted to make it clear that LOTR is indeed one book and not three like some people think it is.
Merry and Pippin were minor characters in the other books but in this one they are drawn into the foreground. Of course in this chapter it is Pippin. I really like that because before the reader wasn't given much of a chance to learn much.
When first reading LOTR I really got to like Pippin in this chapter. I already liked him before but in this chapter I liked seeing how he matured.
When he first came to power Denethor might have accepted the fact that as a steward he wouldn't be the main power in Minas Tirith all his life. But as he got older and no heir appeared he might have begun to think of himself as the "King". Than when he began to look in the Palantir I think Sauron took advantage of this thought or belief and used it to bring Denethor under his spell. Eventually I am sure that Sauron also used Boromir's death to break Denethor. Overall it is a nasty business.
When I read the description of Gondor I immediatly got the impression that the city was in its decline and that all its inhabitants know it too. Faramir mentioned it in Ithilien as well and part of his hope was to see the city restored to its former glory. This state of decay makes the need for victory even more urgent. Or at least that was the feeling I got (which made me read faster
). If evil isn't defeated quickly it could succeed.
The fact that Mordor's shadow is growing rapidly is noticed by everybody's behaviour. It can be noticed by how suspicious the guards at the gate are towards Pippin. Also through this whole chapter there is an stifling atmosphere created by the way things are described and how people act. This chapter saddens me too because it is obvious that Gondor was glorious, and that the decay is now spreading quickly. Actually Moria gives me this same feeling as well. The sadness due to the loss of something great.