This chair is very comfortable thanks to the high back head rest mesh fabric and adjustable arms. After purchasing one for my work office I bought one for my home office.
Frankly this chair is far more comfortable than the much more expensive ergo chair I'm provided at work. I have had zero back pain after using it for nearly two weeks roughly 5 hours per day with frequent 2-3 long sessions seated.
Not a bad chair - I wish the lean-back feature were more flexible though. It only allows you to lean the back (only the seat stays flat) in a few pre-set positions (clicks). The upright is a little TOO upright and the next click back is too far leaned for regular use. And I skipped the silly headrest it really didn't help matters and looks a little goofy. But a solid chair (I'm a big guy) and moves around smoothly on a chair pad.
Purchase the warranty. The chair is great. Very comfortable and not hot like most leather chairs. The headrest is weak and we have broken two of them. Thankfully we got the warranties.
Its hard for me to find comfortable office chairs because of my proportions which include by short overall and with short legs. This chair is adjustable enough and the seat shallow enough that I can sit comfortably without it pressing into the back of my knees. I did leave off the arm rests as I prefer chairs without them they looked perfectly serviceable for those of you who do like them on a chair. The chair went together very fast with the only part that was a little tricky was the additional headrest but even that only added a few minutes.