If you were curious how FormConnect would function on the iPad Mini, it works fine. There are no discernable differences compared to the larger sized iPads. The iPad Mini is a smaller screen and the the fonts are proportionally smaller but the forms are still easy to read.
Holding the iPad Mini feels very comfortable and some might prefer it as it is significantly lighter and can be held in one hand versus the cradling technique used with a larger iPad.
When designing a form, my preference would still be to use the larger iPad, but I did not experience any difficulty creating fields or filling them out. Below is a screen shot of the iPad 2 next to the iPad Mini so you can get a glimpse of the size difference.
Note: I took the photo with the iPad 3 camera and the image is a little blurry. This is not a reflection on the screen resolution of either iPad but rather the quality of the camera and the lighting when I shot the picture.