Sound design wise. Infinite is less halo than anything. Musically sure. Everything else though is off. The warthog now sounds like a civic, gravity hammer lost its sound, energy sword no longer has the hiss. Theres more to sound than music.
Infinite has a strong musical identity that undeniably says "this is Halo."
I vividly remember when "through the trees" was revealed before launch, and the near unanimous response was positive, and glad that it "sounded like halo"