I've been to other aquariums before and this one is by far the nicest one I've been to. I don't believe the price to be bad, I believe it to be very Vegas fitting. Everything is more expensive than the average place but this aquarium was well worth it.
We have an aquarium in Arizona and it's $20 and a 5 minute work through. But here at the Mandalay Bay Shark Reef Aquarium I was able to spend hours looking around and even got to pet a stingray.
I'd say Vegas as a whole isn't really the kind of place you want to take kids but if you have to take them because you can't ditch them off with anyone else, then go ahead and bring them here. It's good for kids, adults, couples, teens, groups, or going solo. Cameras permitted, I took many photos myself. I suggest not wearing high heels as you'll be walking a lot. But if you're use to it then more power to ya. Enjoy the place!