I like the OST as a standalone thing.
But its probably because I was raised on Marty's magnificent score that was only refined as the series went on. There's something about the way he does video game scores that makes them very iconic. Maybe its skills brought over from when he used to write jingles.
Maybe its because its poor implementation in the game, maybe its because it wasn't Marty and you could tell somehow... maybe both. But it didn't give me the same feels the old Halo scores did. The warthog run song, the classic theme, walk in the woods, etc. Even the awesome ODST score and decent Reach score.
Only time I ever felt the music come through was a bit during the walk out of the cave on requiem, the requiem temple, and then the trench run and final run up to the Didact.
And the trench run and To Galaxy didact songs were awesome but I couldn't help but feel they sounded like typical big orchestral epic scores. Which sounds great, but its not very halo iconic.