Took my one year old there for an activity.
Was reasonably priced with a 25% discount. I wouldn't pay full price though.
You could see everything in one hour, so make sure you don't plan a whole day there.
The place in old, no lifts down to the shark/sting rays viewing area, so you have to leave the pram or carry it down al the stairs and back up.
Place needs updating! Was good for my one year old though as he could only last for 45 mins and then he'd had enough.
Didn't get to see any shows, so they would prob make your money worth it a bit.
NO air conditioning!!!

Approximate cost: $20

Oceanworld at Manly is a really exciting place for both kids and adults. I bought a shark dive Xtreme voucher for my boyfriend, where he got to experience the sharks with scuba diving equipment in the tank - he absolutely loved it! There is also a large number of tanks with different species of fish and marine life, educational and interesting!