Apple has developed such great image quality that, to me, it seem a waste to put it on such a small screen as the mini. I do a lot of writing as well as web surfing. The combination of iPad and Zagg-folio wireless keyboard/case is awesome. I would not have an iPad without the Zagg keyboard. There is a Zagg-folio keyboard/case for the iPad mini, but again, there is the issue of screen size.
But the smaller size does have it's advantages as well. the iPad is a rather clumsy size for anything but sitting at a table and using it. The mini would be a much more portable device, more comfortable to use when out and about.
So it all comes down to how a person will use the product. For lots of typing, iPad. For lots of web browsing on the go, iPad mini.