I haven't watched this video yet, but Halo 2's SMGs have always sounded incredibly weak IMO. Halo 3 made them roar (while also making the AR sound incredibly weak).

: Some sounds were missing and I realize it said work in progress, but this is
: the same problem we got with Halo 4. Videos were released and MANY fans
: complained about the TERRIBLE direction they were going with sound design.
: We were reassured that the sounds were not complete and sounded great in
: stereo, surround, headphones, etc. But when Halo 4 was released, many
: sounds still left the impression that they were recorded in a vacuum,
: given a reverberating echo, and just shoe-horned into the game.

: While the other Halo games weren't perfect, the sound was pretty great. Halo
: 4 left MANY of us wondering what was wrong with our audio systems before
: the realization was painfully obvious; nothing was wrong with OUR systems!

Heheh, Halo 4 is all over the map. Some of the sound design is really neat, like the fuel rod gun's explosion's distance-based effect, and some areas in campaign (like the start of Forerunner, if you're wearing headphones) just plain work.

But there's definitely some weird muffledness to the sound, and you have stuff like the plasma staplers.