Got this in a few days ago. To address the one big negative on it I have already removed the headrest because it is unusable. I am 5' 11" and in almost any position the headrest makes sharp contact with the tops of my shoulder blades when I sit properly against the backrest. The problem seems to be that the head rest is positioned low like a neck rest common in many ergo chairs but also well forward of the back rest like a normal head rest would be. I'm looking into 3D-printed extensions that people have designed for it but will probably just leave it off. I read the reviews beforehand and knew that this could be an issue but bought the thing anyway so I can't knock stars off for something I did to myself. Other than that though it's a fantastic chair at its price point particularly if you get one on sale. I use far more expensive chairs at work notably the Ergohuman V2 and Nightingale CXO and while this chair does not stand up to those it makes an admirable effort for being 1/5 the price. The mesh is a bit abrasive but breathes very well. Back support is acceptable the armrests are positioned well and while only adjustable for height the with is set on install and can be adjusted a bit with a 5mm allen wrench. Overall the chair is on the narrow side I think. It's quite comfortable for my 170lb self but larger individuals may want to opt for a bigger chair like the Dexley which also addresses the headrest height issue. The lockable reclining function is fantastic and feels solid which is a welcome change from many other chairs in this price range. Build quality is fantastic for the price point. For those of you deciding between this and one of those ~$100 pleather contraptions at Wal-Mart or what have you get this one. It's a night and day difference in materials and construction quality. Again it's no Aeron but it's quite solid and if nothing else it comes with a 7-year warranty. (Staples if you're reading this that warranty was the deciding factor between this and an Autonomous Myochair)
Very clear assembly instructions and hugely comfortable. This is the fourth Hyken Mesh Task Chair that my family has bought. One of our sons who has chronic back problems reported that after one month of using the chair his back is 100% improved.
I use this same chair at work. I liked the way it felt all day long so I bought it again for my daughter to use in her college dorm room. Her back was hurting after doing school work from her desk but after her chair she no longer has back issues.