I cannot speak for the mini, but they have finally figured out how to provide a long lasting battery in an iPod touch. Of course it took them 5 tries to get it right! My iPod touch 5 and iPad 3 both have long battery use times although the iPad does much better when notifications and WiFi or ON. If I use a lot of WiFi and/or notifications with the touch 5 then the battery drains about twice as fast or more. Those are normally turned off when traveling so that might have an impact on why your battery is lasting so long.

A huge battery drain on the touch is taking photos or shooting video. Those two actions can drain the battery in a heart beat!