My husband and I absolutely rave about this chair. To paint the picture: I'm a NZ size 22 and my husband is 6" and about 120kg. It's safe to say we are both big people.
We actually decided we wanted a Tantra chair after watching How to Build a Sex Room on Netflix. There are some positions that don't work for us, however, there are many that we can still have fun with. I personally wanted this chair as I have chronic pain and sex can be uncomfortable: however with this chair I can ride him the entire time without getting any aches or pains.
He's also happy because this chair let's us successfully do reverse cowgirl: which is one of his favorite positions, but which has always been difficult for us.
This chair is completely made of foam, which means no uncomfortable structures digging into you. It's also very good foam: it can hold my husband and I, and handle our movements, without any issue at all. Because it's made of foam, it's also light enough to move around when you need it.
It also has two covers, both are machine washable. The first layer is a water proof layer and the second is a more comfortable material layer.
This chair has already improved our sex life in the short time we've had it.