I am currently listening to the complete soundtrack recording
here. The link does not allow jumping or choosing, so it's something to play through from beginning to end.
There's no denying that Howard Shore is the composer! The beginning is very much connected to LotR themes - I assume we'll be seeing Frodo there. The dwarves' theme that we've heard in "Far under the misty mountains" shows up in variations - I do like that melody.
Have you already pinpointed favourite pieces?
edit - Ah, I just now am hearing the Rivendell theme from LotR!
edit: Concerning the final song - I just read the list of composers and it does not include Howard Shore. I am relieved. Quite frankly, a song that needs five (count'em - 5!) composers can't be good!
'nother edit - I've also heard the Lothlorien theme, presumably for Galadriel's appearance. And the orcs/wargs have music that sounds very similar to what we heard in LotR, especially at Orthanc. I suppose it's natural to emphasize the connection of this "prequel", as Jackson is using the story. I do hope there's not too much repetition though.
I am amused that there is a piece called "Brass Buttons"!!