I suspect that the knife owner shut up because he didn't know what he was talking about.
So long as you don't mistreat them, Shun hold a blade rather well. The problem is that they're cut at a sharper angle than most European knives (16° vs. ~20°), so the blade is more delicate, and so is more prone to go out of alignment, especially if you use too hard of a cutting board. Cutting on a glass, ceramic, metal, or marble surface will slowly destroy a European blade ... you'll horribly screw up a Shun if you do it even once.
Note that Wusthof and Henkels recently (in the last 3-5 years) went to a steeper angle as well, some as low as 11°, so they'll likely have some of the same problems. (mine from those companies are older, so I don't know for sure).
You can also damage them if you're too aggressive with the knife (hacking / chopping, instead of slicing) or if you try to use it on hard items (bones, frozen meat), and they're more prone to damage if you hit them against something; I took the tip off of my Shun because I laid it in the sink ... the tip was against the side of the sink, and the weight was enough to break off a mm or so at the end. I then got another chip in it (hit against a metal utensil in the dish rack) all in my first week.
Even with that chip, and regular use over about 5 years, it's still holding a sharper edge than my Henkels, Wusthof or Sabatier blades, and it's the knife I use the most these days.