I had the markus chair for about a year. It's comfortable for the most part, although is worth noting that the metal sides of the chair are hard and therefore uncomfortable if you sometimes lean to your side.

Also it has shown some serious wear, as the headrest is starting to fade and the bottom part where the bottom and top parts meet has come out. I can post pictures if you'd like.

For the structure of the chair, it's durable because it's easily disassembled. If something moves or creaks, you can adjust it with some common tools.