Not been yet but I'm planning on heading down in the next couple of weeks and will, of course, bring back some photos - though I'm expecting it to be a standard British aquarium - pleasant but unremarkable. Maybe it'll spring some surprises, though.
It's pleasant enough but does not take very long to go round. Nothing Earth-shattering in the stock but Giant Pacific Octopus and Nautlius are always nice to see.
I wouldn't say it was worth travelling to on its own but being small it pairs up pretty well with the Zoo for a day out (from a zoo-nerd's point of view, the Zoo has a more interesting set of fish species, though!).
Labelling has a bit of catching-up to do, as well!