The AV system proposed was pretty straightforward. The BC-STV and Ontario's MMP were defeated in 2009 and 2007, respectively. I think it's pretty hard to get the electorate behind changing electoral mechanisms. It might be a communication issue, but I think voters get comfortable with a heuristic of "if it ain't broke, don't fix it," not realizing that FPTP is flawed in a multi-party system. Without reform, there's Duverger's Law...first-past-the-post leads to a two-party system over time.
This video explains the UK AV proposal::
I think that electoral reform will be more likely in Canada if the Conservative Party of Canada fragments back into Progressive Conservative and Reform factions. While some are saying that Layton's new Québec faction will test the NDP, I think Stephen Harper's majority government will put him to the test with social conservatives. Before, he had the crutch of having a minority government as a limiting factor on what he could do. He's stating he wants the Conservatives to be the natural governing party of Canada, replacing the Liberals. I think that's a stretch, which I'll blog about in the future.
Twitterversion:: [blog] AV in the UK? Election reform referendum en route to defeat in the UK. @Prof_K