Restore from backup - new iPhone 5

Hi,

I just got my brand new iPhone 5, upgrading from my 3Gs.
I really want to transfer the data from my 3Gs to the new iPhone, but I heard the "restore from backup" option transfers a lot of 'junk' and slows the iPhone (especially if the backup is from a jailbroken iPhone), so it's not recommended.

So I wanted to ask: is it true? it's not recommended?
I don't want to start with a new iPhone already full of "junk".

And if it is true, is there another way to restore whatapp history, sms and maybe also games history? (without jailbreak - since iPhone 5 doesn't have one yet)

Thank you!
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