It's very hard to describe, but I would say that it almost gripped my back. Felt nice every time I sat in it. I'm not fond at all of plush/soft seating.... this felt more like I was a block of lego mounted to another block of lego. 
Yeah, I’m not trying to tell you what you should/shouldn’t find comfortable... use whatever works for you! :-)
For me though, something that fits like lego is pretty bad, if I need to sit in it for more than 20 minutes at a time, because lack of back/torso movement is one of the big problems with chairs, especially ones that encourage sitting with the pelvis shoved forward and the back curved, and don’t allow you to sit straight in them. This stretches out all the muscles and joints, and without some movement and time to relax/reset, they get really stressed over time.
One kind of interesting thing I heard about a couple years ago: Airports started intentionally moving baggage claims further away from the gate, because it turns out after someone has been sitting for 2–8 hours, their muscles are all strained and very susceptible to injury. If the baggage claim is close to the gate, people will get there quickly and then stop moving (either stand in place or sit down to wait), getting bored and frustrated, and then injuring themselves when they try to lift their heavy luggage. After forcing people to walk for 10 minutes in between, injury rate goes way down, and people arrive at the baggage claim just when the bags are getting there, so they also don’t get as impatient/frustrated.
