I didn’t find the lumbar support to be very supportive and the seat rocks back when I lock the chair in place. FYI I’m 5’3”. My feet hangs a little from the chair.
I've been using this at my office for about 4 years now. I'm 5'11" and my shoulders barely touch the bottom of the headrest but it didn't bother me after a few days. Beyond that I have zero complaints. Liked it so much I bought the same chair for my mom.
I can tell why this chair is a favorite. It is quite comfortable and supportive with a nice design. I recommend it. There is a plasticky feel to the build of the arm rests and casters. However it shouldn't be a reason to not consider this chair.