Let me add a few adjectives. This chapter is dark and deep like a pool under the mountains. It is not scary like the Barrow-Downs chapter was, but it is just dark. The beginning shows the horror of horrors - the words "in the name of Mordor!" spoken in the Shire itself. And this is the last time we see something from the Shire (unless you count Sam's vision in the Mirror) until the Scouring. And I believe, even though there is not any actual evidence on that, but this is the feeling this chapter gives me: that this is the moment of breakdown, the moment from which the evil in the Shire starts to accumulate rapidly and culminates in the murder of Lotho. Why the passage gives me such feeling, may have several reasons; if I were to try to find some concrete points, I'm not sure, but I can mention at least the fact that the Horn-call of Buckland is blown: and what more, it is blown even though it "had not been sounded for a hundred years, not since the white wolves came in the Fell Winter, when the Brandywine was frozen over." With the same horn, as we read later, it also ends. Also, the character of Fatty connects both the occassions. I completely agree with what
Esty said - Fatty's character here is given the actual experience of horror, but I'm inclined to think that this really served him later well and here is the source of his later courage as a rebel leader.
The chapter is really quite long, at least when you compare it to the several former ones, but I must say I was very surprised when I read it ("oh, it's the end already?"). It's so "epic" so that it seemed to me maybe shorter than the chapters before.
When I read it for the first time, I remember I liked all this stuff about the "Great Enemy" ("Huh! Who's that? Yes, that's Morgoth, I know, I heard the name somewhere - but he must have been cool! And 'Sauron was only his servant' - what's this? THAT Sauron who is the great and indestructible evil around here was just a servant of this one? Gotta read the Silmarillion."). On the other hand, I did not want to read the poem of Beren and Lúthien - way too long and uninteresting (for a 8-year old boy). Obviously, even the reader's taste changes as he grows, as I really enjoyed the poem when reading it now. It is just beautiful!
I said this chapter is deep. This reflects these tales of Beleriand, Beren, Lúthien, Silmarils and even Gil-Galad. It's all too ancient, and indeed, Strider's speech about it is really quite long. I would say very long. Had I been a heartless critic or editor, I'd say: "Mr. Tolkien, we don't care about nonsenses from ancient ages. It makes no sense there and has no actual connection with the story. You may as well skip it and save some paper." But I am not a heartless critic nor editor, and I like the fact that it's there
What I like very much are also all the things with Rangers - we learn quite a lot about them (that they come to Weathertop, and between the lines we learn also that they keep some paths in the hills etc.). I was always wondering who were these Rangers who were recently on Weathertop, where were they going to and from when, and whether they knew about the Riders and what happened to them...
And there's a very good trick concerning Gandalf in the chapter. If you take care of it when you read, Strider mentions at the beginning of the chapter that if Gandalf follows them, he would be heading to Weathertop as well. Note please, we still don't have a clue what happened to Gandalf! It's most likely, from the current view of the characters, that he's simply lost for good. But as the chapter moves on, there are several almost anachronistic looking quotes that seem to imply that the characters actually expect to find Gandalf on Weathertop, like they knew that he was following them! We, as readers who have read the book more than once, of course know that he indeed is - but how do the characters know? But, of course, by the end of the chapter, this is verified (or at least made likely) by finding Gandalf's tracks and "message" by him on Weathertop.
This chapter is also where we can "see" the Nazgul in their true shape. This is also a touch of the unknown, and I liked it very much from the first time I read it: as well as all the information about the Riders that Strider says to Merry. By the way, I just got a funny idea: why is Merry so curious about the Riders' nature, like whether they can see or so? Is he collecting information for further use?
Or more seriously, is he overcoming the experience of his encounter with a Nazgul in Bree by asking about such things? When you know something, you are not afraid of it anymore...
And, concerning the Nazgul attack. It seems strange that the narration about the old days and Beren and Lúthien almost fluently passes into the Nazgul attack. And it does not seem contrasting in any way to me, which I find odd. But is there also something more - I'm getting the strange idea that the narration held the Nazgul back from attacking. They attack only after Aragorn finishes the tale. It's just the weird feeling: had the tale to be completed so that the Nazgul were allowed to attack? And what would that mean...?
And one more thing I just thought I might point out.
Esty in fact said it, but I will emphasise it a little bit: this chapter starts with a Nazgul attack, and ends with a Nazgul attack. What more,
Esty said it starts with a knife and it ends with a knife. I think it's a clever literary figure, but even if it's just a coincidence, it's nice.