Yes putting in the casters was tricky but I got them all to go in. Assembly was not very difficult. The trickiest part was how long it took to get the height and tilt configured so that my sciatica stopped acting up. The tilt does not lock at any angle there are actually only about four settings including all the way up and back which didn't work for me. Luckily one of the middle two tilt settings worked. Once I got everything where it should be this chair is exactly what I needed. And since I'm only 5'8" the headrest fits too.
Received my chair yesterday. Firstly the chair was supposed to come on Friday (Dec 23rd) for the holidays but I was informed at 3 PM on that day that it would be delayed until Yesterday (Dec 27th). So that was already not a great start. The chair arrived with lots of cosmetic damage to the plastic that wraps around the metal spine. After struggling for a bit with it I decided to just take the plastic off. I believe that it should not have affected the chairs function but its never fun to have a chair that is broken before you even sit on it. As for the chair itself it is fine. The reclining system is less customizable than I would like. There appear to be only 3 unique levels of recline - STraight up (little forward) Very far back and then too far back. The system seems like there are just "locks" that the reclining bar slides into. The headrest also suffers from the same issues - it only has 2 different angles both of which are uncomfortable for me (ended up taking it off). However - The rest of the chair was great especially when considering the cost. Easy to assemble the mesh is high quality and it feels durable (other than the superficial layers that were broken during shipping)
Per other reviews removing the head rest was a great improvement to the chair. I'm not sure of the stature of the person that it would fit but it certainly wasn't mine. It is non-adjustable. The lumbar support is decent and is adjustable.