The D2 extreme was my first good quality knife. I had been wanting a Kabar for awhile and almost jumped on the USMC, but the steel and sheath of the D2 swayed me. And it looked cooler, although I now own a USMC and the stack leather is really awesome.
Yes, the steel is a bit of a bear to sharpen. But edge retention is very good. I brought mine to my mom's a few Easters ago and batoned firewood and kindling all night, then proceeded to prepare a prime rib after a quick cleaning. The tip was still pointy as hell and the edge was right there with me still.
I have since stripped the coating, put a nice patina on her and sharpened the top swedge. (I'll try to get a pic up). I normally dislike serrations but I feel that on a blade of this length they do not drastically take away from the function. It is one of my favorite knives - period. When I go out camping next week this baby will probably spend the majority of time on my hip.