Visiting Turtle Islands National Park is an incredible experience. I highly recommend it. If you're lucky, you'll be able to witness the birth of some little turtles and see them run around on the beach, or watch the mother turtles lay eggs.
The centre is well-built; the awareness is clear and it works. Rangers are there to supervise the tourists so that they don't bother the turtles. I loved learning that some turtles are left to themselves, with the aim of preserving other species which depend on turtles in the food chain. We're here to help protect turtles, but in an intelligent way, without harming other species.
Expect to spend most of the night outside. The accommodation is basic, but for one night, we make do. Furthermore, the food is good and we don't feel hungry, so it's all positive. A "must do" on your Malaysian trip.