Well, I visited the Melbourne Aquarium today. Its been a VERY long time between visits. To put this into perspective, I think the last (and only) time I have been they had not yet acquired penguins and it definitely was before Merlin bought it.
I was going to post a very short review but I saw this thread and thought perhaps here might be a better place to park my opinions, since I think in review I will shed some light on at least why I dislike this place so much.
Let me start by saying I haven't been to a huge amount of Aquariums in my life, but I have been to some significant ones and a number of places with extensive Aquariums as part of their displays.
Among the notable: Georgia Aquarium, Osaka Aquarium, Montreal Biodome, The California of Sciences and closer to home, the Sydney Aquarium (pre Merlin).
Melbourne Aquarium is terribly, terribly mediocre by comparison. I think its biggest flaws can be put down to this:
1) Melbourne has no grand oceanarium. This is the centrepiece of most Aquariums, the main attraction. Melbourne's main tank is pretty small. And whats worse, With its "doughnut" design where the visitors are in the middle and the main tank wraps around them, there is not really any singular area where the back of the tank is more than a few metres from the glass. Its not even close to competing with other Aquariums I've seen.
2) And there is not really any other exhibits that has any sense of grandeur. Or spaces. Because almost the whole building has very low ceilings and the corridors are also narrow.
3) And whilst the first two issues are the real crux of the problem, I can't help but also comment on how appalling all this is compounded by the poor layout. The whole thing has a very unnatural layout with some major accessibility issues. People where backtracking, it was hard to know if you where going the right way, wondering what floor you where on.
And all this is before Merlin came and added, literally, disco balls to the ceiling and an assaulting mess of dramatic music in speakers. The mermaid statues aren't even a big deal given how bad the lighting and sound is. But really even all this is all pretty irrelevant given how horrendously mediocre and small the exhibits are to begin with.
At almost $50 per adult, save your money go to the zoo instead (which has seals, reptiles, penguins and some marine fish) and then wander through Royal Park to The Royal Melbourne Children's Hospital - which actually has a much better, grander reef tank than the one at the Aquarium.
You'll have a better time and have $10 left in your pocket.