According to the release (which cites various articles, etc.) ...
... "Giuliani slashed government spending, Romney increased it."
" ... Romney failed to recover jobs lost in recession."
.... "Romney's health care plan increased taxes on businesses."
... "Romney proposed nearly $400 million in business tax increases."
Update: Romney responds:
“What we have here is a fundamental disagreement over tax policies affecting American families. Mayor Giuliani crusaded against the line-item veto and fought very hard to keep a commuter tax burden on hardworking taxpayers. Governor Romney strongly disagrees with Mayor Giuliani on those issues, since the line-item veto helps reduce wasteful spending and families ought to be protected from higher tax burdens, instead of having their mayor file lawsuits in court in an effort to keep them.”
– Kevin Madden, Romney for President campaign spokesman