I’ve been doing some work using Marmalade and cocos2dx. These are my cents.
Pros.* Marmalade allows you to work crossplatform on the same project (some people can work from VS while you sit in XCode).
* Marmalade offers a solid simulator so that you can preview your project quickly no matter which environment you work in.
* Marmalade probably speeds up your build process quite a lot once you’ve sorted the configuration.
Cons:* It’s probably easier to get all configuration done using only cocos2dx. We’ve had some problems with getting everything working in Marmalade, but it might be our inexperience * Marmalade isn’t free.
If you’re only targeting iOS and Android I think cocos2dx standalone will work, but if you’re considering even more platforms, or need to work in a bigger team
with multiple coders, I think Marmalade can be a good way of going. I guess it all depends on your project. I’d try setup a project using both methods and evaluate.