The Instax mini 70 is a more recent release than the mini 8 and, as a result, has updated looks and a few more features than the 8. It also weighs a fair bit less than the mini 8 thanks to its use of two CR2 batteries instead of the three AA batteries found in the 8. That isn't necessarily a good thing, as CR2 batteries aren't as common as they used to be, and may not be easy to find locally when the first pair runs out.
The mini 70 has a bit more of a premium look and feel to its build and controls than the cheaper mini 8, and carries a few more features. The lens is motor-driven and automatically extends when the camera is switched on, and a flash icon indicates when the flash is charged.
The motor drive means the lens has the ability to change position for different focus zones, extending the minimum focus distance to a much closer 0.3m, something the mini 8 would need its optional close-up lens to achieve. This closer focus distance means the camera is self-portrait ready straight out of the box, with a small mirror out on front of the lens for framing such images.
The zone focusing is coupled to whichever shooting mode the camera is set to. Instead of the ring telling you which mode is appropriate for the scene, the user chooses the mode based on their shooting scenario and the camera determines the appropriate exposure for them.
First, there's the standard mode, where no icon is displayed on the rear LCD. Hitting the Mode button cycles through the Macro, Landscape, Flash and Hi-key modes. Next to the Mode button is a button to toggle the self-timer and another to toggle the Self Portrait mode. The camera automatically determines whether or not a flash is needed for a scene, and usually will not fire in bright daylight, especially when in Landscape mode.
The mini 70 does a great job of adding features without making the control interface too complicated or confusing for beginners, making it a great balance of user friendly handling and affordability.