About as good as it gets for a European made carbon steel knife.

These knives are not for everyone.  Some people find non-stainless to be too much of a chore.  Others hate full-finger guards extending from the bolster; and still others prefer harder steel that doesn't roll as easily as whatever the heck the better Sabatiers (including K-Sabatier) use.

Before going into the specifics of this knife let me clarify that despite the fact that many manufacturers have the word "Sabatier" as part of their brand names, the brands are distinct.  There are many, a few are good, and a very few are very good.  K-Sabatier is among the very good; and, for what it's worth, it's also the original.

THE DRY SPECIFICS: 

Handle:  K-Sabatiers have excellent handles.  They're POM, which is a very durable sort of plastic.  The handles are among the most comfortable western-style handles I've ever used.  They're as good or better than such stalwarts as MAC Pro, Misono UX-10, and Wusthof Classic. 

Fit and Finish:  Generally very good.  That is, the handles fit, you won't find many grind marks (except right around the edge), they don't ship with stains on the blade and so on.  However, out of the box sharpness and sometimes edge geometry can be less than good.  I don't see that as much of an issue, in that these knives fall in the class of knives which should only be bought by people who can do a decent job of sharpening and edge maintenance on their own.

Blade Alloy Characteristics: (There are four, by the way: Strength; Toughness; Edge Taking; Edge Holding).  The alloy used is neither strong nor strong; and, in that it impacts edge holding, that may be the biggest weakness the knife has.  The blade is extremely tough; but is nevertheless very easy to sharpen.  

The edge profiles (repairs, thinning, resetting the bevel, and otherwise adjusting the geometry) reasonably easily.  It sharpens extremely easily.  It also maintains easily on any appropriate ("fine" or finer) rod hone (aka "steel).  The last is a good thing, because as I said, the knife is relatively soft which means it "waves" fairly easily.  However, frequent steeling is a small price to pay given the knife's other outstanding characteristics.

It's an old fashioned European knife with a full finger guard bolster.  Some people find the guards difficult to sharpen around.  I don't, but it's a big deal with a lot of people. 

Consequently, I'm dinging the blade and performance scores for the softness and fingerguard design.

On the other hand...

INTANGIBLES and BOTTOM LINE:

The 10" K-Sab is the most agile chef's knife of the size I've ever used -- and I've used plenty.  The geometry is perfect.  The French profile is not only more agile, it's lighter than a German profile.  Add to that, the knife is about as thin as modern cutlery gets.

For the cook with reasonably good knife and sharpening skills, the K-Sab au carbone, has a unique quality in the hand.  It's a gestalt which seems to say "let's go to work boss."

In terms of overall use, the only competitive western-handled, mass-produced, carbon knives are the Masamoto HC (more than twice the price), Masamoto CT (less, but still more than twice the price) and a couple of other carbon Sabatiers.  

Not for everyone, but if you like carbon, can live with an HRC well south of 58, and a bolster with a full finger guard... HIghest recommendation.

Buy while the Euro is crumbling.