As far as aquariums go, Ocean World is tiny and the tour is quick. Yet, there aren't a lot of parks where you can pet an actual shark for less than $10 admission. So in that sense, this place is a winner. Plus you get a small seal show to end the tour.
As others have said, the staff here is uniformly pleasant and helpful. Throw in the huge gift shop and it is a must-do when in Crescent City. The kids will like it, especially the shark. If you're lucky there will be some shark eggs to view.
Tip: If you don't have AAA, just pick up an Ocean World flyer from one of those ubiquitous tourist brochure racks. This will garner you a 10% admission discount as well.