Went during the day on a weekday, so there were no lineups at all. Obviously this isn't possible for everyone, but I'd recommend staying away from weekends as its totally overcrowded.
Anyway, this is no doubt the best aquarium (without mammals) I've ever seen. They have incredibly large tanks and use some creative techniques to display them. The best tank is definitely the shark tank. You can stand on a slow-moving conveyor belt and look all around you as a tank wraps overhead creating a tunnel that you pass through. It's quite a feeling to have sharks and sting rays pass over your head.
It's not cheap at $30, but considering the amount they've obviously invested in this place, I'd say it's a fair price.