Hi. I only have one folder in D2, the Viper Free and I am far from being a steel expert. I can only tell from my empirical experience: compared to other similar folders (with similar thickness, geometry, grind, etc.) I own in S30V, I would say its harder to sharpen (I use normally a Lansky System at home and a DC4 in the fields), therefore I normally need to resort to coarser stones or powered grinder.
Edge retention is, in my experience, a little less compared to S30V but nothing I would have noticed if not when extensively working with wood whittling/carving. For me it works best when I dont refine the edge too much, if its toothier it cuts better and last longer. Corrosion has never been an issue for me, but, fair to say, I maintain my knives (i.e.: I sharpen or refresh the edge at the end of their week in rotation, clean them up, disassemble if the case, lube, put some protective oil and store them properly). It can get some superficial stains if let wet or dirty but I always managed to clean with a cloth and a common steel cleaner (the thing I use for kitchen sink, hobs, etc.).
Overall I have good experience with D2, nothing sticking out for good or bad though, I would say a decent blade steel.
My Viper Free: