The best thing about this is that it WORKS, as vouched by me and friends and family who take turns using it whenever they visit :o) and it's also versatile because it's portable enough to take it to the office if you need to to. I would say it works best on high backed chairs (like an office "executive" chair). It works very well also in my opinion if you place it on the floor/wall edge so the back of it is leaning flat against the wall. That gives the best result in my opinion. But for most people it's best on standard chairs with a high supportive back. Won't be good on a sofa with low back nor it is any good with lean back chairs (because your weight pushing against it might cause the massage rollers to push too hard and not very pleasant and possibly painful). Very soft seating materials are also not recommended since they don't give enough support for effective functioning of the cushion.
The disappointing thing is that the instructions are sparse. Although it's easy to operate and you can figure it out, it doesn't give much advice on the types of chairs to work with. It says it will work with just about any chair/seating but I'm not sure that's entirely accurate, as I discovered it took a few days of trial and error before finding out for myself.
The gentle heat function is an added superb feature, and I would say if you are considering buying a shiatsu massage cushion, then this one (or the deluxe models) with optional heat function should be on your shopping list.