VERY easy to put together.  I was pleasently surprised.  2 downsides for me:
1) the chair is actually higher than I thought.  I am 5'6" and my feet dangle at the lowest setting.  The foot bar does not ergonomically work for me, so I need to get a stool for under my desk to place my feet on.
2) there is no way to adjust the depth of the chair, so I find myself sliding off of it because the seat is too short.

The back rest is extremely comfortable. It wasn't expensive, so I will keep it until I find a better alternative, and then give it to my kids who are less picky (and don't work from home 2 days a week and need a comfortable chair!).