I have been a half dozen times, and yes, it is almost always packed. The weekdays are better than the weekends. The aquarium itself is pretty awesome. They have some really cool exhibits... the open ocean exhibit is the best. Attached is a terrible pic I took of the main viewing window at that exhibit. The silhouette of the person in the lower left gives you an idea of the scale of this window (and I didn't even get the whole thing in frame). To get to the main viewing window, you walk through an underwater acrylic tunnel that is about 150' long or so, which is also very neat. It is a sight to see, for sure. The reef exhibit is also a pretty neat one, as is the Mississippi river biotope exhibit.