Size limit on app download when using 3G
iOS and Windows Phone has size limit on how big apps you can downloaded when you’re not connected to a Wi-Fi-network. Windows Phone has a limit on 20 Mb and iOS has 50 Mb. Android has not that type of limit, but an APK on Google Play is limited to 50 Mb, but you can add extensions that are much bigger than so.
When are you downloading apps to your phone? It's often when you sitting on the bus or waiting for something. Do you have a Wi-Fi-connection then? Often not.
I think it could be a good thing to think about when developing apps. If a user found your app and cannot download it, the chance that they choose to download another app instead is big. If you have big content in you app, you maybe can have it on a server and download it when the user starting the app.
Probably the user don't need that content from start and you have some time to download it, if they navigate to a part that need the content, show a loading dialog that tells the user that content is under download.