Pros:

K-on!
It actually works.
Removes the old boring voices, and adds better cuter ones :'D

Cons:

None.

Conclusion:

Really Loved it! :D


Solution Here Again so it wont get lost:
Its a nice mod and since many people are having issues getting it to run i will post what i did:

1) of course donwload the file first
2) get GFCscape (the first entry on google(nem´s tools))
3) save the voice folder in C:\Program Files (x86)\Steam\SteamApps\common\left 4 dead 2\left4dead2\sound\player\survivor
4) open the l4d2 anime voice.vpk with gfcscape(dont put it in your addons folder!!!)
5) Delete the voice folder
6) drag and drop the voice folder out of gfcscape
7) in steam go to your games and rightklick left 4 dead 2
8) click on properties and then select the option above creating a desktop icon(start optionen in germen...suppose its starting options in english)
9) type -console in the window that pops up
10) select ok, close the properties tab and launch the game
11) in the options under mouse and keyboard select developer console enable
12) close the game and reopen it. now a console should appear. type snd_rebuildaudiocache into the console
13) a loading screen should pop up and take some time till the loading bar ist filled. when it is the console should pop up again. when it does type exit into the console
14) try to lauch a game(for testing a singleplayer game is suited best) and press z. now choose some of the options and check if you have normal sounding anime voices(from the K-ON! characters) or if the voices are very slow or simply non existent if that is the case check 15)
15) make sure that you didn´t drop the l4d2 anime voice.vpk file into your addon folder. in either case redo step 12) to 14) untill succes.

I had the file in my addon folder and the voices were very slow. 

I had to do everything from step 12) twice, but now it works perfectly. NICE MOD!!!

ps. enable the subtitles, so you know it when others give you a signal or are simply reloading...cause "yay" is not very informative XD


Note : i tried to post this as a comment but i would always get the "no urls in comments" error...

if i have any mistakes in my checklist please feel free to comment

Pros:

I like it! :) Cirno!

If you've noticed (Wolfy) i have all your cirno weapons :P I like em..

Cons:

None.

Conclusion:

Cirno! :D It looks awesome! :D Really love it! (x

Pros:

New look!
Sukone Tei! :D
Favorite creator ;P xD
Not same crappy and boring look of the old Pump Shotgun

Cons:

None!

Conclusion:

I love this pump shotgun! :) Definitely a keeper! :D

Pros:

Vocaloid!! :D
Its really cute and a new look! ^^

Cons:

Uhm.. Miku looks really skinny and super long for some reason..

Quality on the incapped pictures are kinda low.. But i can work with that if Miku gets shortened a little bit and not too skinny lol..

Conclusion:

I love this! Just those little bad things i found kinda bothers me...

I really love this one! I hope you continue fixing these.. /:

Pros:

Neptune.
Nepgear.
New look.
I hate rochelle.. LOL.

Cons:

Well.. I see everything fine.. So NONE!!!

Conclusion:

This is a new cool look to them :D Just... The only thing that bothers me is the voices... xD

Pros:

Miku!!
Ahhh better one than the original one! :DDD
New look!

Cons:

NONE

Conclusion:

I love this one :D Kinda got tired of the original red one e.e 

Pros:

John Deere
Green colour
Unique change :P

Cons:

None.

Conclusion:

Well i've actually have not found a good chainsaw, but i really like this one.. so its a keeper :D 

Pros:

Really funny.
Trick people to thinking they have to stay inside then suddenly see the plane going down.
Reactions, Priceless.

Cons:

None.

Conclusion:

It would actually be really nice if you made it for Left 4 Dead 2 too. lol..

Pros:

Really good texture
Smooth shooting
New look :P

Cons:

None

Conclusion:

Enjoy this new look for the M60..
Really good job done in this gun! :)

Pros:

Anime
Fits in perfectly
Always hope tank appears to listen to the music xD

Cons:

Dying from the tank because you wanna listen to the song.. xD !!

But other than that. NONE.

Conclusion:

It's awesome! :D I love it! :)

Pros:

It's funny
Kinda does make you wanna die lol

Cons:

none

Conclusion:

It's pretty good, i mean to not just hear the same death sound, better to hear something different.

Pros:

its K-ON!
Something new to look at! 
Yey  a concert! :D

Cons:

CONS?!?! WHAT.. ARE YOU CRAZY!?

Conclusion:

i love this!!! :D i'm so keeping these! :P

Pros:

Great Map Idea
REALLY FUN with friends
Great building
Unique

Cons:

None

Conclusion:

This map is amazing!
Must be played with other people, because the bots... Are really useless!! Lmfao.

Pros:

Color
Picture
new look!
Miku!! :D
It's a keeper! :P

Cons:

None!

Conclusion:

I love this one, the colors are just right for it! :)

Pros:

Really good map
Gets pretty difficult
Pretty big map, enough to run in circles and live xD

Cons:

Should add more things scattered around the ground..
More Molotov than pipes or boomer biles.. since they're kinda useless o.o since its tanks only..

Conclusion:

Well it works if you run in circles, but there might be times when you get surrounded and probably die. xD
Really enjoyed this map, it was good! :)

Pros:

Color.
Picture.
Unique look! :D

Cons:

None...

Conclusion:

I really love it! :D Really unique! xP Wouldn't change it for anything! :P

Pros:

Cute, funny, ANIME!

Cons:

Nothing!

Conclusion:

Lmao.. thats funny xD... And i got so many mods from you! :D I got like all your weapons xD

You're just awesome! D: Add me on steam if you ever can? ;~;

Pros:

Awesome skins!
Cool new look!

Cons:

NONE!

Conclusion:

Andreas is just a crying kid.. ahaha.. This is awesome! <3 btw.. im downloading all your custom guns.. xD Putting them on mine.. ahaha xP

Pros:

Adds suspense
makes things more scary
goes with the game..

Cons:

None

Conclusion:

Really scary when the tank is coming! Never know from where!

Pros:

Really good textures
Sounds better in my opinion..
And the color is good

Cons:

None

Conclusion:

I'm liking these more than the regular ones..

Pros:

Nice, and not boring... A lot more than just the regular one..

Cons:

None..

Conclusion:

If only there was another color... Like red... But its still good! (:

Pros:

Huge improvement! Looks a lot better, more detailed and colored! :D I love it!

Cons:

None!

Conclusion:

I'm keeping this one! >:D

Pros:

Really nice! It's easier to spot, the glowing looks amazing! I like it!

Cons:

None!

Conclusion:

Might keep this forever! xD ahah its really cool.

Pros:

Detailed, Color, Texture, more spotable! Really nice i like it!(:

Cons:

None! 

Conclusion:

Really useful, easier to find adrenaline shots... i like it! :D

Pros:

Animated, realistic, really good color...
What else can i say! 

Cons:

None!

Conclusion:

it's amazing! :D Gonna keep this one for sure!

Pros:

A lot of detail, and texture, the animation and the lightning are really good...

Cons:

Perfection.

Conclusion:

I'm gonna keep this one! ;D

Pros:

Show's other's HP, Better picture images.. A lot more helpful..

Cons:

None... really!

Conclusion:

This GUI is probably the best.. and i might not go to another one...