After about 5 or 5 days I really like this FlexFit™ Hyken Mesh Task Chair Black (UN59460) I sit in it about 6 hours a day. Very adjustable and comfortable.
The chair took 30 minutes to assemble. It is comfortable and once set up fits well into my home office environment. Two caveats. At its lowest setting it still sits up a little higher than my previous chair which means that I am now a little higher over my non-adjustable height keyboard tray than before. This is not the chair's fault so just make sure you measure your particular desk. Also I wish the arm rests were a little bit further away from the seat. This is not adjustable once you tighten the screws that mount the arm rests. It would be great if they provided an additional inch on each side as my elbows currently fall just at the outside edge of each armrest.
The chair took me overall around 20-25 mins to build upon arrival. One thing I would recommend people putting this chair together for the first time would be to attach the back of the chair prior to attaching the arm rest as that will make your installation process much quicker and much easier. I'm 5'10"and everything just feels and fit almost perfectly I have set the lumbar support to the highest setting and for the headrest I have it set to the medium setting. The headrest gets uncomfortable when I set it to the highest level as I can feel the plastic of the headrest hitting my back. Only time will tell how long the mesh holds out but overall I'm satisfied with my purchase.