I consider myself average height (5' 10") and find the headrest digs into my shoulders. So uncomfortable that I have removed it. Disappointed in that aspect of the chair. The chair without the headrest feels "okay" so far. But not a product I would buy again.
Overall the chair is comfortable and well made. The assembly is very easy to do with thorough installation instruction. I usually seat on the chair somewhere between couple hours to five hours without getting up from a chair so it has to be comfortable. I would give 5 star if headrest is bit taller. I am 5'11" and when I seat upright position the bottom of headrest keeps rubbing against my shoulder so I have to lean little bit forward. Although I can adjust headrest it's limited to tilting mode not height of headrest.
This makes the 3rd one of these chairs that I have purchased for various desks in my home. I LOVE this chair. It is extremely comfortable for my body but I especially love that it can act like a rocking chair. My most creative thinking is done while rocking.