It's rather odd (or maybe not) that "Best Answer" to this has gone a comment on the UK referendum!
Signor Renzi shot himself in the foot by making this a resigning issue. It meant that a lot of people would almost certainly have used it as a way of geting rid of him. If I'd been eligible to vote, regardless of what I felt about the proposals, I'd probably have voted "Yes" to keep him in power, which is not what these things should be about.
Interestingly, however, in an exit poll a small majority of voters claimed to have voted on the issue itself, and not on anything else.
Italians by nature trust their politicians even less than we seem to (and not surprisingly, given their history) to the extent that apparently they'd be happy to see a clown in power.
Plainly Signor Renzi should have adopted the Russian approach? Want, say, to extend the Presidential term by 50% from 4 to 6 years? Avoid all the hassle of a referendum and simply put it before a corrupt and biddable parliament :-)
Sorted.