Most of my wardrobe is only a year old, so I don't really know what's going to hold up or not.
I will say that I bought some very finely textured sweaters from VS last fall that did not hold up well at all. However, to VS' credit, I took them back to the store about a month ago to complain (I felt that they had stretched out quite a bit, and I had another item I'd bought at the same time that was pilling after only maybe 6 washes). They refunded all my money! So that was a very good experience.
As for my pre-YLF days, I have to say that *anything* I have bought from J. Jill has held up like iron. I have skirts and tops that I have worn multiple times a week for three years before they started to die. I remember one linen top that I loved to death and wore tons. On its third year, I took it out of the washer one day and noticed a hole on the back of one of the shoulders; interestingly, the hole was not at a seam. I repaired it with a little iron-on stuff (can't remember what it's called) and continued to wear it. A couple of washes later, *another* hole appeared! Same thing, not at a seam. It turned out that the shirt was literally disintegrating from use, as it began springing multiple holes. Had to toss it.
After these items were made, J. Jill upped their sizes (size inflation), and now I am sized out. I lament that often, because their clothes are excellent, excellent quality. Highly recommended!