Pretty cool if you're staying at Mandalay Bay, but I don't know that I would make the trek all the way to that end of the Strip to see it otherwise, but then again I tend to like wildlife that makes me want to pet it. Like Scott W noted, you can get through in about 20 minutes. If you like listening to the audio tour and reading the info on the exhibits, you could probably get an hour out of it.
The komodo dragon was a nice attraction since you don't see them everywhere. With sharks, rays, turtles, and lots of tropical fish, there's plenty to see for a marine life fan. And if you insist on taking your kids to Las Vegas, this is a great place to visit rather than parking them in an arcade for 14 hours. Be prepared for the obligatory souvenir photo at the beginning and exiting through the gift shop as usual. Those kids will find something they want!