The gardens are part of the grounds of Leuralla (an early twentieth century mansion that houses a toy and railway museum), which is located across the road. Leuralla costs $15 to enter, but these gardens are only $2.
The cost isn't much, but if you're here on an average weekend, you can see pretty much all of it without actually going inside, as there's no hidden spots you can't see from the road while you pass by. Except down into the amphitheatre that is, which is made of sandstone and Bathurst slate and fits right into the Blue Mountains setting.
It would probably be more worthwhile to come here on a special occasion; the gardens can be booked for weddings and performances and can seat from 300 (just using the amphitheatre) to 1000 people (including use of the lawn).