Caviar's tasty. I doubt I've ever had the expensive stuff - I've never bought it specifically, only had it at buffets and weddings and such - but it's got a rich, slightly fishy taste and a kind of berry-with-seeds texture. Some sushi stores sell a similar dish which is, I believe made from salmon roe and is typically bright orange in colour, which is still tasty but with a somewhat different flavour and texture.