I've decided to vote yes: You are not bound to express more than one vote so it adds flexibility.
Many in the 'Major' parties like the first past the post idea because it gives them total power to do whatever they want once they've conned their way in with only 30% of the vote.
One of the arguments used against AV is that it will lead to more hung/coalition parliaments.
I rather like a coalition government

at least it makes things a LITTLE more representative of the electorate.