Not the best chair I have used in my life but if you can get this on sale it is worth the price. If you have access to a Herman chair go with that instead.
This chair is comfortable nice armrests and the mesh is nice but the headrest is completely useless when sitting up. It only adjusts up and down not forward/back. I had a pillow from my old chair that I am trying to use to close the significant gap. Not sure what the purpose of it is unless you're leaning back and looking at the ceiling? Going to give it a try but I might have to return it.
After almost a year of working from home due to COVID my lousy back/neck/shoulders were really suffering & I was getting headaches regularly by the end of the work day. This chair was a great investment and is enabling me to work w/o discomfort.
For reference I am 6'1". I bought the Dexley over the Hyken for its larger size thinking it would work for my height but the bottom of the headrest rests against the top of my shoulders. The lumbar support at its highest setting is still an inch or two too low and puts pressure on my lower back instead of providing lumbar support.