I am the proud owner of several other Miyabi Birchwood knives, and purchased the Nakari as soon as it came out!
The Birchwood line is made out of SG2 steel which is quite hard, and keeps the blade edge nice and sharp.  When they do need sharpening, its so easy to bring the knife back to the original edge, which makes me feel like I'm always working with a brand new knife!
The Birchwood handle is so stylish and looks great in my new kitchen.
Nakari knives are so useful and can be used for mincing, cutting, slicing and dicing.  The shape of the blade is wider than a chefs knife which makes it really easy to scoop items once cut.  I can work with the Nakari without experiencing hand fatique, and find myself grabbing it when I need tons of vegetables for soups, stocks and stews.