The chair was delivered before I even received a shipping notice so imagine my surprise to find the box waiting for me when I got home. Assembly was quick and very easy with all the screws sealed in individual packets numbered to match the instructions. The only tools needed are your hands a little muscle and the allen wrench (included in the box). The chair fits perfectly under my desk all the adjustments work perfectly and the chair is VERY comfortable. It has helped relieve my leg pain when I sit for an extended period of time at the desk.
I've been using this chair for 8 hours/day this past week and all in all it is pretty comfortable. The back support is good--the back stays put when sitting upright but still doesn't take too much force to push back to recline comfortably. I don't really have much use for the head rest since I usually sit up pretty straight all day. The seat could be a little more comfortable though--after 8 hours it does feel like the sides pinch slightly where they curve up.