Love this thread, as Shige is probably one knife that I studied in depth, and tried to understand the reasoning behind every step in the process (some on a theoretical level, of course)
It's also one maker I have a lot of respect for - level of worksmakship, attention to detail, consistency. I haven't come across many J. makers (in fact very few) who painstakingly shape and taper the tang (invisible part of the knife) even though it results in a clean handle installation. Things like that speak volumes to me.
Steel is a simple carbon steel probably from Uddeholm. Holds a good edge but the steel has no alloys that would contribute to great edge holding, though on the other hand, the knife sharpens very easily to a screaming sharp.
A transition between the tang and the spine is very nice (forged and filed/scraped by hand), geometry is great, weight would put it in mid-heavy or medium knives, depending which Shige you get. Early ones were heavier and thicker in geometry.
Very thin at the edge, planes brought down to zero on most knives I have seen. Very easy to initiate a cut and food separation is superb, especially on thin knives. Easy to thin down the road.
Finish is very good on kasumi and great on kitaeji knives. Some of the nicest hand carved kanji I have seen.
In all, this knife does look and feel like a quality hand-made knife. In other words, it need no "help" to sell.
Reactivity, microchipping, and easy to bend (on thin knives) are the things that make it a less than perfect knife, but folks find these a manageable trade-off compared to other things the knife offers.