I know it's been touched on a bit. The New York Times did an article about it around six months ago and Greg Pease wrote an article about it shortly after.
A friend of mine here in Las Vegas was actually lucky enough to get some. There are three makers of pure Semois blends and his son's mother-in-law who was in Belgium was able to acquire one of each for him. He was gracious enough to bring them to the West Coast Pipe Show and share them.
Incase you don't know the Semois tobacco was originally Burley seed that was planted in the Semois river valley in Belgium, I believe somewhere near where the Battle of the Bulge was fought, around 150 years ago. Over time the climate and soil have morphed the flavors of the leaf into something very unique and unmatched in the world.
When he opened the pouch to me it smelled like an old codger Burley with a bit of a cigar and herbal smell noticeable as well. It's a very dry tobacco. The pouch consists solely of Semois leaf and contains no casings or top dressings and I've heard it doesn't have any humectants applied to it, which I would believe because it's rather dry even in a pouch just opened. Since it's so dry it's good to pack it a bit tighter than usual. It takes a light nicely and burns pretty well as long as you've packed it a bit tighter than usual. Burns down to a nice white ash. Seemed to burn a bit quicker, but slowing down a little bit was good. As for flavors it's one that you should have a number of bowls of before deciding on. I had three bowls over the weekend and still am at a loss to describe it. I did sort of get the cigar like flavor as well as that earthy herbal flavor that has been noted by others. I sampled the mildest of the blends and so I didn't notice much as far as nicotine levels. My friend did sample the strongest version and he said the nicotine was noticeable but not overwhelming. Overall it's a nice blend that if you ever have a chance to sample a bowl of you should regardless of if you're an aromatic smoker, a Virginia smoker, an English smoker, a VaPer smoker etc.