I have arthritis and lots of very painful lower back pain, a lot of which is due to bad posture while I sit like a true saddo for hours on my pc, having forgotten about my back spasm until it hits me (and does it like letting me know lol).
I already have a reasonable quality office chair with an ergonomically shaped back.., but I am a little 'diddy' (5ft 4) so it was hard to maintain good posture.
I purchased this as it seemed deep enough to allow me to sit with knees raised, forcing me to sit with my back fully against my office chair back.
And yes, it definitely works. The reason I have given it a 4 rather than 5 stars is it is quite wide, which means I can't place the foot rest as far under the chair as I'd like, the wheeled legs get in the way.
However, it has definitely reduced my episodes of back pain and I can even feel a bit less like a 'height restrictred' diddyman because I've been able to raise my chair from the minimum height setting lol.
Its gotta be good for the price. I'd recommend to anyone. I've had it for over a month, seems strong, doesn't move around when I don't want it to but allows me to slide it to a better position when I do very easily.