I had an interview at SIU yesterday (I'll try to fill out an interview form later soon). The faculty were very nice (the few we met with) and the facilities were amazing when considering the low low tuition (around $35,000 each year) and low living costs.
The interview is very laidback, they ask everyone the same questions, so there are no oddball questions, just the basics, why dentistry, where do you see yourself in ten years, strengths/weaknesses.
The writing prompt is very easy too, one hundred words on an ethical situation.
I liked the school a lot, but it isn't a school like Penn or Columbia. Plus the town and surrounding area are very dull. I would give it a shot and see if it suits you. Also, they don't have a very high rate of specialization, about 1/3 to 1/4, but they do have some opportunities (perio and endo maybe) and are hoping to expand soon.
Hope this helps!