I'm with This Old House: Anything named the "Turkey Cannon" should really launching poultry into the sky. But until someone else rectifies that oversight, the Cannon does look like an interesting way to cook a turkey, using an elevated metal tube filled with the liquid of your choice to cook a modestly-sized turkey in just a couple of hours—hopefully while keeping it moist inside. It's essentially Beer Butt chicken with a more freedom to jazz up the liquids.
The two reviews on Camp Chef are pretty positive, and the one offered recipe sounds delicious:
We cooked it on our gas grill. We filled the cannon with apple juice and Jack Daniel's. We soaked hickory chips and then placed them in an aluminum foil packet with holes punched in on top to give the turkey a smokey quality. Our 12.5 lb. turkey cooked in approximately 2 hours. It was moist and picture perfect.
The Turkey Cannon is $25. It's got me wondering if I should try to do a turkey on the grill this year.