I've been using this chair for about 3 weeks now, over 8 hours per day, and it's definitely replaced my old chair. It's solid, well built, from quality materials. It's very supportive at the base and in the lumbar area, with the Max version having just the right seat length to reach the back of my knees whilst allowing my legs to bend (I'm 16 stones and a bit, at 6 feet tall).
The range of armrest adjustment is very good, and it's nice to see that each position locks nicely in place. The seat height range is great for me, and in general the chair is lovely and large without burying me.
The assembly went well and quickly, with all the required parts and tools perfectly packaged in the box. An extra pair of hands and eyes might have been nice at a couple of points but I got there on my own.
A couple of suggestions I have for the manufacturers are to put the fire resistance label under the seat base or off to one of the sides (so that it can be re-sold or given to charity in the future), and to clarify what is "the right way" when fitting the control lever unit to the base of the seat, because it's trial and error figuring out that the socket for the gas lift should be towards the rear.