Highly recommended!
It heats up quickly. I usually turn it on and go do chores for 15 minutes and then it's already heated up and ready.
I'm not suuure it goes up to 75C as it claims to, but it certainly gets uncomfortably hot after I'm in it for 20 minutes inside.
The size is super comfortable for me, I'm 150cm, I just sit indian style, without the chair, take a book in with me, a flashlight, and some lukewarm water and I have a blast for 30 or so minutes.
I DO wish the head hole had zippers to it instead, I tried duck-taping it shut but I might try something else to minimize the heat from escape even more (not to say much heat escapes from it).
I've already recommended this to two of my female friends who suffer from joint pain: this is a massive relief and having it at