Currently Being ModeratedJul 13, 2013 10:37 PM (in response to breadmonster)
I am probably late to answer you, but this will help others with the same problem that you had.
Definitely the best way to do it is by using your iTunes or iCloud backup and restoring it to your new iPhone. But if you have any reason not to do that, you can do what I did.
It is quite easy, you need only a desktop app that can access your inside iPhone data, I used "iExplorer" for the Mac (they have a PC version too).
1. Plug the iPhone you want to back your messages to your Mac
2. Browse its contents with the explorer app in your desktop
3. Find this path iphone/apps/whatsapp/documents
4. Copy wallpaper, statuslist.plist, contacts.sqlite, chatstorage.sqlite to your desktop
6. Plug your new iPhone, the one you want to restore the messages
7. Browse its contents with the explorer app in your desktop
8. Find this path iphone/apps/whatsapp/documents
9. Copy backed up files to your new iPhone
10. Unplug...restart Whatsapp...and there you go...
Of course you need to have Whatsapp installed in your new iPhone and already activated with the SMS code.
In my case, my iPhone had a software problem that wasn't letting me make any calls, carrier response to that was easy, full iPhone reset and the phone problem would be solved. Nice...but after the reset, I couldn't apply any iTunes backup to my phone in order to restore, data, apps....messages...etc, cause I would be restoring same phone problem.
Almost everything is in clouds, so "manually restoring" my phone to previous state wasn't a problem, the only things that worried me were photos, Skype and Whatsapp history, cause I had a lot of business conversations that I wanted to keep. So photos was easy too, just download camera roll and you are ready....skype was easy too, using the same iExplorer and backing up "main.db" and restoring it again.
So I hope, this helps.