Pros:

+ Very Fun
+ Excellent Visuals
+ Felt like an official campaign
+ Not too hard, not too easy 
+ Has all the traits of a good campaign

Cons:

-Finale
-2 Tanks spawning on top of you.

Conclusion:

This was by far the most enjoyable add-on campaign that my friends and I have played. The details to the maps are fantastic and the gameplay really flows along right to the end. Someone already mentioned that it feels like an official campaign and they were spot on. I don't really like the end much, but its not as bad as some of the above reviewers are saying. Being in the wrong place at the wrong time in the finale can be annoying though (resulting in instant death if your not careful ~ i.e. thrown into the ocean by tanks).

Pros:

looks great - way better then original
makes you want to use the rifle more
great sound
can't see myself ever going back to the original, can i dont see anything that beats this.

Cons:

I would have liked to have seen a longer barrel.

Conclusion:

all in all my favourite replacement for the rifle. really nice weapon.

Pros:

Looks cool
Lovely sound to it
Beats all of the other m16 replacements i have tried

Cons:

There is always a better weapon, i just have not come across it.

Conclusion:

Beats all the other replacements for the m16 that i have seen.