The headrest is great. it is not hard to put together. It leans back to a resting position. It does not work quite so well when you are not leaning back but on the edge of the seat. I have only had this a few weeks and just use it a few hours a day but I like it much better than the other chairs for use on the computer. I do recommend this chair. It is not expensive either.
Overall I really enjoy this chair. The mesh is breathable the ergonomic controls have a decent range but I am 6'2" ~210lbs and it is just a bit small.The headrest hits the top of my shoulders at best and the base of the chair is a bit slim. If you're my size think twice otherwise its a great chair.
This office chair is very comfortable. It does not have all the bells and whistles like some $800 office chairs but its about 95% there for a fraction of the cost.