You haven't? You should try it--it's pretty good, very versatile. It's mostly a dessert, but whatever sauce you pick to go with it really decides on the flavor. Mitarashi's sweet and savory, so you don't have to worry about it being overpowering.
[He sets down the ball he's been holding to roll out the last few, shifting to let her watch more easily; even with Itachi's sweet tooth influencing him over the years, he still prefers savory stuff most of all. Mitarashi is a nice compromise they can both enjoy.]