I’ve only been sitting on this thing for 5 or 6 hours, but so far I notice it’s about 9000x more comfortable than my old chair. Comfort may not actually be the “right” word for the chair. It’s more like I can sit in it and not have my back screaming in agony. I work from home so I spend many many hours in my computer chair. For the first time in a long time, I’m not hunched over looking at my computer screen. I’m actually sitting upright. That’s what these ergonomic chairs are made for, to make you feel comfortable with good posture, and not hunch over everything and feel like crap.
I really have NO idea why I didn’t get an ergonomic chair earlier. I’ve been on the computer for extended periods of time since I was about 10 years old. Always using crappy wal-mart chairs, that were NOT designed for what I was doing. Even when I did have money, all of it went to processors, video cards, speakers, monitors, and nothing went to my chair. The chair remained a POS from wal-mart at all times.
Now that I’m 19, I’m starting to feel some back issues develop. Those 9 years on wal-mart chairs for countless hours are starting to take hold. However, I think with this chair those problems may go away completely. (Only very slight pain from leaning over all the time has developed)
Anyway, the best way to describe the feeling of sitting on the Knoll Life Chair is “good”. Mine has adjustable arms that go up and down and side to side, which I would recommend. I think these are “High Performance” arms. Adjusting the height of the arms along with forward/backward and side to side really comes in handy depending on how you’re sitting or want to sit in the chair.
The seat moves forward slightly depending on how you sit on it, and you can slide it forward or backward as much as needed. You can of course lean back in the chair as well, and adjust the tension.
Overall, I have to say I’m super happy with this chair, it’s the first time I’ve felt comfortable sitting at my desk in years (No joke.) Even though I did not pay retail for this chair and bought it at an eBay auction, I think it’s actually worth the retail price of $808.
I was actually very scared of ordering a chair online without trying it out in person, and the only reason I got the knoll life chair was because of the auction and I didn’t want to pay more than $400 for my chair. Unfortunately, there really aren’t any shops nearby that sell “performance” task chairs. I was going to get the steelcase leap, but so far I’m glad I didn’t. This chair seems perfect for me. I really like the breathable back, and steelcase doesn’t have that.
Conclusion
Finally, a chair I WANT to sit on.
Update
6/16/10 – After sitting on this chair for a few months, I can form a more full opinion. My opinion hasn’t really changed – it’s still the best chair I’ve ever sat in. 
My back has not hurt since getting this chair. It makes the couch seem uncomfortable due to less ergonomic support Has also shown no noticeable wear, usually by now a $100 chair would have plenty of wear.
Definitely worth every penny.
