The tour was fun. I didn't find it scary, though some of the stories were both interesting and gruesome. Our guide was good, with lots of interesting tales of life inside, escapes, executions, ghostly visits by ex-prisoners, and the appearance of a ghostly cat called Tripod (he had three legs).
I'd also recommend them for their great customer service. Having booked a few weeks in advance, one of our party (my 11-year-old niece) became a COVID close contact and had to isolate for the week, just before the tour. The organisers were so helpful in re-arranging another date.
So, excellent customer service, great tales of a darker side of Brisbane's history, and a fun way to spend an evening with friends or family.