When Call of Duty: World at War was announced to have a four player co-op mode as well as split screen play, we were all pretty happy.  Then the Zombie mode was announced and we jigged with excitement.  Finally a Call of Duty game with co-op!   And even though we reviewed the game fairly positively there are some glowing problems, specifically with the split screen mode.
While Call of Duty: World at War isn't a very long game, it's not one that can easily be played in one sitting.  But that's just what the developers are asking of split screen players as there's simply no way to save your progress in this co-op mode.  Even though we pointed out the problem in our review of the game as well as an episode of our podcast, people are still getting bitten by it.
Our forums are filled with folks furious about this missing feature.  Co-Optimus member Lo_Rez writes:

COD:WAW is not a true co-op game if you cannot SAVE your co-op game. This is highly misleading, to the point of being a bait and switch to the consumer.

Another member had this to say:

My brother and I live for co-op. And this game really screwed us both. The only reason we bought it was for the co-op. And we just recently realized that we can't save it after we made it to the fourth level. And we wanted to play split screen on xbox live too, and of course you can't do that either. The developers really ruined World at War.

We know it's difficult to disclose all the features of a game on your box, and we know it's partially are job to provide this kind of information to our readers, but perhaps there's something more developers can do?  In such a severe case like this I would think a nice little disclosure when selecting the mode would apply.  Nobody likes playing for three or four hours straight only to realize that all your progress is going to be lost.
Like we said in our most recent Co-Opticast, we realize development cycles are difficult and tight, and sometimes concessions have to be made, but where there are concessions there also needs to be some sort of disclosure. 
So pass this article on to a friend, get the word out.  Let developers know if you are going to implement co-op, please do it right. 

you have to play solo to unlock all the maps.... so you can start from any map you would like....

but the rusian -sniper-founten leven is missing more

badirontree is exactly right. Co op mode is intended as an enhancement to multiplayer. You can't save for the same reason you cant save in multiplayer (in fact, you can't even play all the levels in co-op). You can unlock the various levels by completing them in single player campaign mode. Nicholas, I think you missed the point.

BTW the first user comment you quoted is flat out wrong on every point (so is the second one for that matter).

A lot of people pick this up, put it in with a buddy next to them and try to play through from the beginning in co-op.

It's a huge glaring oversight on their part. If you look at other games which support split screen co-op (Halo 2, Halo 3, Gears of War 1, Gears 2, etc) they all allow you to save your progress in this mode.

Playing single player to unlock co-op is plain idiotic. It's just like we mentioned in our review, you have to complete single player to unlock a co-op only mode (Zombies) - ?

Who comes up with this stuff?

Besides, everyone is entitled to their opinion. Unless the argument is about whether the Xbox was made by Nintendo or Microsoft, then it's up to the gamers.

Co-op gamers know what they like. Saving progress GOOD, Being forced to play a game solo in order to play all levels in co-op BAD.

A lot of times, I get games solely to play it with someone else. If I had to play it alone first that would ruin it. I would know things before they happen and I like to be surprised WITH my friend.

Anyway, I haven't play COD5, but considering how it was implemented, there should have been disclosure to the consumers.

Point taken and I agree that it probably would have been nice to be able to save your progress. However, to say they used a "bait and switch" and that "The developers really ruined World at War" is going a bit off the deep end.

I guess everyone has to have something to be fanatical about.

I'm with you on this.

To me, Halo 3 was a huge letdown because three of the four players were forced to be Elites, despite the usual abundance of human characters on screen in most of the levels. Also, you can only play co-op splitscreen with two people.

In Castle Crashers, if you play co-op online and start on a level that is beyond where you've already gotten, your progress is ignored. Baldy and I joined two others online and beat the game...only to find myself back where I had left off in single-player. If we had started one level back, it would have saved my progress and let me beat the game. Weird.

Are these games ruined? Not at all. Just odd quirks that make ONE scenario sour out of the HALF DOZEN available.

The Zombie mode in COD5 isnt coop only, in fact I only played it single player before taking it back. (rental)

I also agree on the stupidity of no save for SS coop, that should be listed somewhere on the box.

You have to get to it via the "Co-Op" menu...

Does anyone have a save file for the PS3 that just has easy mode passed off in single player that I could download? I want to play through co-op with a friend without spoiling any suprises. I also dont want a 100% passed off save file either because I do eventually want to play through single player passing off stuff on harder difficulties once I have gone through cooperatively.

Never mind everyone.

I found EXACTLY what I was looking for here: http://www.ps3savegame.com/US_Saves.aspx

So now I can play co-op and then play through normal-hard modes on single player too.

This is perfect.

Thanks to anyone that started looking for a file for me. I'm good now.

Or you can play single player and beat the campaign to enter zombie mode.

I had misread what you wrote. For some reason, I thought you were complaining that it was NOT co-op...

INFORMATION!
I have discovered that if you use this method you cannot earn trophies. SO, I have found another solution. Simply make an extra account on your PS3 just for when you want to play co-op with your friend. You can then use your standard account to play through normally on your own terms and still earn trophies while having the extra account ready for when your friend stops by and you want to play some split screen co-op.

I hope this helps someone somewhere because I couldnt find any information about this stuff anywhere.

I guess I should also note that once you have completed the single player campaign on your standard account, there is no reason to have the extra one. I purely wanted this because I want to play through co-op without having played through in single player once already, and the lack of saving co-op progress makes it very impractical to do so otherwise unless you play the whole thing in one day.