The big advantage of plurality system is it generally returns a majority government and apparently we're like dead keen on that. Or something. It's looks so ridic at this point though - European Elections, council elections, the Welsh Assembly and the Scottish Parliament all have some form of PR. And it pisses me off because we're a left-leaning nation and that isn't reflected in the MPs returned.

ETA: The Lib Dems have been calling for reform forever; it's like their big yummy Golden Egg thing.