I had my first shave with a japanese razor last week (not a tosuke), and its definitely an experience. I shaved only with the concave side...super easy, smooth, comfortable shave on the left side of my face, not so much on the right. Until I went ATG, then it was the opposite.

And thats the thing about Japanese razors...it seems like it'd take an awful lot of practice to be able to shave one side as well as the other, given the different handle position. I dunno if I would ever be able to shave both sides equally well, unless I had two razors, with the concave grind on opposite sides (a "lefty" and a "righty" razor if you will). I still love this thing, and will keep using it, and attempting to get as proficient as possible with it.