I saw one at the Deer and Turkey Classic Show last Feb in Bloomington IL.
One of my friends bought one, but I thought the sight picture looked crowded and might be difficult to use in low light. There is also the issue of having to align one pin to center the sight, and using another to aim at the target/deer. Maybe too confusing in the heat of the antler.

In spite of my first impression (I did not shoot using it), I've heard that they can use the sight just fine with out any hiccups.