Several days ago, I was in the same situation like the OP, right after having got a new iPod Touch5 a few days earlier.
I decided to go with the iPad4 over the mini.
Deciding factors for the iPad4:
Retina display
Larger screen (good for reading, browsing the internet, taking notes and etc)
More usable keyboard in the landscape mode
Decent durability (I read reviews the mini is not as sturdy as the iPad4)
I have to admit the Mini is definitely lighter than the iPad4, which is heavier than my old iPad1. But, it is still way lighter than a typical thin-and-light notebook computer.
I will consider getting an updated mini in the future when it is equipped with the faster A6 chips, retina display and larger storage. But, I am not going to get the current one.