It is a high quality chair with smooth rolling casters and excellent adjustability. I didn't think I would use the headrest but I love it. The most important factor in a rolling swivel chair is stability. The chair should not rock or wobble as you move. My old chair's poor stability is the reason I bought a new one. The Hyken chair is very stable.
I have sat in other mesh chairs and the back tends to be soft and unsupportive of my lumbar. This has a nice additional support so you get the benefit of the mesh seat with a firmer lumbar. I gave it 5 stars for people under 6'. I am 6'3"+ so it is a 4 start chair for me. There are 2 things i wish were improved. The head rest would be perfect if it adjusted 2"-3" higher and I would prefer an extra 1" on the seat pan depth. Neither are deal killers and my disc don't bother me nearly as much as my old traditional chair with a solid seat pan. Despite the areas to improve for people my height I would still buy it again as I have yet to find a good Tall mesh chair.