I've only had the knife for a couple of weeks, so I won't be touching on edge retention or ease of sharpening yet.
First impressions are very positive. The knife feels substantial, but not unwieldly. Good balance, and I find the bolster comfortable when using a pinch grip (although I know this isn't a universal opinion). The edge from the factory is razor sharp, and has no problem starting a cut with zero pressure on tougher items like citrus and vegetable skins. Very little slicing drag for shallow cuts. I'm not brave enough yet to use it for breaking down joints or other edge-punishing tasks, but I don't feel like I need to be particularly delicate with it either. I'm looking forward to seeing how the edge ages and what the sharpening experience is like.
The main drawback (which I hesitate to call a drawback, but rather a consequence of the design decisions made) for me is the width of the blade behind the edge. The substantial blade adds a sense of durability, at the cost of increased drag and sticking during slicing operations. It's not going to unseat my carbon steel santoku for thinner, more delicate work.
Overall, I think that the Mk9 will end up as my go-to for most general prep work. The combination of comfort, edge, and durability will keep me from reaching for specialty knives quite as often.