Pros:

-"WTFBOOOOMMMMM"
-Sound works, occurs when Boomer explodes... but that leads me to the cons:

Cons:

-Sound timing is off-> the BOOM part of the phrase happens after the boomer explodes
-Sound quality isn't terrific, but it's audible
-No "HAHAHAHAMUAHAHAHA"?

Conclusion:

-I'm not even slightly familiar with how modding works, but this just my opinion as a player using the mod: I can't see this as being something that's easy to time. In order for the 'BOOM' to happen right as the boomer explodes, the 'WTF' would have to happen before the weapon/bullet hits the boomer. And even so, with all the other noises (i.e. gunfire, common infected screams, explosion noises, general ambience, etc.) probably going on, it'd be hard to hear the wtfboom sound, anyway.

Pros:

-Beautiful texture, model and overall design
-No blatantly obvious errors in visuals or performance
-Bad@$$ replacement for the ugly-as-hell default MAC

Cons:

(Minor details)
-Reloading animation is a bit off (I'm assuming it's since the default MAC and the kriss vector vary greatly in shape)
-Continuous shooting shows the gun being almost completely stable while the screen vibrates (not a lot of visible kickback) 
-Silencer is slightly misaligned

Conclusion:

You'd have to be somewhat picky to not like this replacement for the MAC 10.
Again, there were just little tiny itty bitty details that could be fixed. I could be totally wrong (as in there's no error with the mod), or I could be missing something totally obvious. 
Regardless, I would recommend giving this mod a try.

Pros:

-Great detail and design
-Didn't notice any sort of misalignment
-Much more aesthetically pleasing than the default SCAR

Cons:

-Grip looks a little funky (but that's merely an opinion. It's not a problem that needs to be fixed)

Conclusion:

This mod made the SCAR one of the favorite guns to use in L4D2, which is great since I was so desperate to get rid of the ugly default SCAR look. 

Pros:

-Storyline is perfect
-Dialogue is perfect
-Difficulty is perfectly balanced
-Finale is perfect
-Everything is perfect
-The cake is a lie.

Cons:

-What part of perfect don't you understand?

Conclusion:

Undoubtedly the best campaign I have played. The attention to detail is impeccable and the music as well as other little details make the campaign extremely enjoyable. 

Download it. 

Pros:

-Great detail, very clean and aesthetically pleasing. 
-New sounds are awesome

Cons:

-None as far as I can tell

Conclusion:

A worthy download and a giant step up from the default L4D2 pistols. I highly recommend this mod.