yeah, i have been to one of their retreats in M'sia last year and it was an unforgetable experience.
I remember going there tense and reserved, wanting to resolve issues behind a skin condition (eczema) that I've had since young and all the emotional problems that it caused such as low self-image, as well as a desire to improve my relationships with my family, especially my dad, whom i was having lots of issues with, becos he was so strict and cannot express his emotions well, and i always felt intimidated by him.
By the end of the retreat, I felt amazing and my heart opened up. And I cannot remember another time where i felt so connected with the world. I managed to resolve the anger and other negative feelings that I've held inside for so long about both the skin condition and the feeling of being controlled and intimidated by my dad since i was young. Of cos, my skin condition didn't disappear immediately, but it has been improving steadily since then, and more importantly, I've come into acceptance with it. I also made great friends with the other participants in the retreat who shared the journey with me.
So to answer your last question, for me, it is deep and able to bring out childhood issues, but it's not intense at all. So if you wish to resolve something that has been troubling you for a long time, I would definitely recommend attending one of their retreats as it was really effective for me.
Hope this helps.
Cheers