Seeing the statements above, you can see where this is primed to be Apple's biggest seller.
With the full sized iPad you heard people talking about buying one for themselves. For maybe one for them and a spouse. With iPad mini you are hearing plans to buy multiple devices off the bat with it being an easy gift' for the upcoming future.
Of course a lot of that hinges on the price/value being right. I know hard core Apple fans 'cringe' at the very notion of 'value' being brought into the equation, but items ~$300 fly off the shelves as impulse gift, 'treat myself items'. Whether it be golf drivers, Coach purses, etc. There is a reason the iPhone is subsidized to be $199 or $299....because that's an amount that people are very comfortable spending without it being a 'huge' purchase.
iPad sales were tremendous. But I think the mini could potentially double the sales of the larger model.
A total stroke of luck for Apple. They had pretty much written off the smaller market. And they gave everyone a year headstart. But once they saw there was a market for it, they were able to quickly retool to make one and can literally print money because a lot of people will want to stay within the Apple ecosystem.