Man, I forgot just how good the Halo 4 OST is, it's not Marty level, but it's still really damn good. I just hope they bring back more motifs for Halo 5. Judging by E3, where they had the E-dorian theme play at least 3 times, I think we'll hear it. I really want to hear the whole theme in all it's glory to return.
I was listening to it yesterday and I'm in agreement, even with the first installment. I think the main problem I have with the community's outlook on it is that we can only have Marty-style music or Davidge-style, rather than both. As much as I like the classic Halo themes, I also think Davidge and Jinnouchi brought a lot of solid work to the table - 117 is really emblematic of 343-era Chief and gives him a really meaty assortment of sound, while the Halo theme would work well for... well, actual Halos. To Galaxy for the Infinity, and so on and so forth.
As far as minor "character themes" go, Intruders is one of my favorite flavor-of-the-times tracks ever, and I think Revival's got my favorite alternative take on modern music's "BWOONNNNNGGGG" trend ever. You guys remember those mildly deep synth "brrrrrrms" in the Concept Art Trailer? The climax of Revival (the "DA-NA-NA-NA-NAA-BWOOOOOWWWW" thing) is the more finished product of that, in case anyone didn't notice.
Immaterial is honestly probably my favorite Davidge piece on the soundtrack, even though I wasn't a huge fan of Composer's aesthetic or gameplay - it's just so damn depressing and
ethereal, and I'd love to play a Halo game that takes that atmosphere and expands it into a fugue cosmic.