Days out: The former home of the Greater London Council now houses a giant aquarium. Do the sea critters do it justice? By Emma Haughton
Everything about the recently opened London Aquarium promises to impress. Its location, for instance, is none other than the vast Edwardian monument of County Hall, former home of the Greater London Council, which boasts unrivalled views across the Thames to Big Ben and the Houses of Parliament.

On paper, the aquarium's vital statistics are equally spectacular. Billed as one of Europe's newest and largest displays of aquatic life, it took two-and-a-half years and pounds 25m to build the 41 tanks into the 170,000 square feet of floor space. Between them they contain one million litres of specially filtered water and some 30,000 fish across 350 species, including all the old favourites of sharks, conger eels, stingrays and piranha.

Two huge tanks which descend the three levels of the aquarium offer uninterrupted views of marine life from the Atlantic and Pacific oceans, while another 39 tanks cover a wide range of other briny and freshwater habitats: the reef and living corals, the Indian ocean, the mangrove and the rainforest, the tropics and European waters. In the touch pool and beach pier you can develop a more hands-on relationship with various sea creatures, with the opportunity to tickle the curiously friendly rays, and handle hermit crabs, starfish and mussels.

The visitors

Emma Haughton, a freelance writer, went with her husband Jonathan Rees, and their three children, Joshua, six, Flan, four and Zachary, two.

Joshua: Some of it was good and some of it wasn't very interesting. I liked the conger eels and the tiny ones that glowed blue and red, but some of the plain fish were boring. I preferred the big tanks where there was room for loads of fish, they were much better than the small ones. I think a lot of the fish were nervous and scared. I liked the lights in the ceiling that made shadowy pictures on the wall, but the lights in the tanks gave me a headache looking at them.

I touched the ray and it felt all slimy, then I touched another one and it felt all rough. I was a bit afraid to touch them, but it was the best part, even if I didn't really like it. I think really I preferred the Sea Life centre we went to in Brighton.

Flan: It took a long time and I was a bit bored, but I liked saying "cheese, cheese" to the fish and playing a joke on them that I was going to give them cheese. They don't have cheese in aquariums.

I touched a flat fish in the water and it felt like a pancake, but I just hated the way that the water tasted like salt. I like sharks, so I pretended all of them were sharks. Actually I was scared of the sharks, but I couldn't really be scared because the glass was there. Sharks can get bigger than a giant, but I know giants don't exist. I wish I was a fish.

Zach: Oooh, look, fish, Dad! Fish, look, Mum, fish!

Jonathan: I can think of worse ways of spending an afternoon, especially if it's raining, but this didn't fill me with enthusiasm. Considering how many brilliant exhibits there were, it was really undersold. It felt completely unfinished and lacking in atmosphere - with a bit of decoration it could be vastly improved. Some of the tanks seemed very badly designed; if there were more than a few people looking at the exhibits you could see absolutely nothing until they moved on, so you were standing around waiting a lot.

Since this cost pounds 25m you'd have thought they could have invested a bit more on information. I'd have liked to have seen a lot more about the fish and their natural habitats - what was there was pitifully small, and often in really awkward positions. I did like the way the place was laid out, a warren of underground chambers, although it wasn't obvious whether you'd missed things. With a bit of extra thought and attention it could be a lot better, but as it stands, I preferred County Hall with Ken Livingstone in it.

Emma: I love fish and am pretty easily pleased, so it was a surprise to be so disappointed by an aquarium. Everything conspired to give a poor impression: the entrance system seemed chaotic, the cafe was dull, the bar was closed, and the floor in the toilet was muddy - with loo paper strewn everywhere. The whole place had an air of being put together in a hurry.

There was little attempt at atmosphere beyond a few mangrove trees, and the bizarre booming and trickling sounds piped across the sound system were more irritating than anything else. And I was amazed how little information there was. At most places like this you are overwhelmed with facts and displays, but apart from the odd video placed awkwardly in the corridors, and undersized pictures of fish with a line or two of description, there was simply nothing to tell you about what you were looking at.

Even so, the larger tanks were very impressive, especially looking up from the bottom at the fish swimming above your head - there's such a hypnotic beauty in their perfectly synchronised shoals. Sadly, however, the luminous lighting in the tanks made it difficult to watch for long periods, and there was something about their expressions that was dispiriting. I know fish always look disconsolate, but in this case I think they might have a point.