Same sex couples have been marrying for several months, and there has been no visible ill effect. Our divorce rate is so far unchanged, and heterosexual marriage rates are essentially unchanged as well, so any kind of "defense of marriage" nonsense seems not to be needed in reality.
There is a lot of advertising, mostly against the support, including many ugly lies. Fortunately, and speaking well for the people of this state, it does not seem to be working and may even be backfiring.
There is much to be said in favor of equality in marriage laws, and Jonathan Rauch says it much better than I can. He has been writing on the subject for many years, and has studied it in depth.
Even a moment's reflection shows the fatuousness of "Let them eat contracts." No private transaction excuses you from testifying in court against your partner, or entitles you to Social Security survivor benefits, or authorizes joint tax filing, or secures U.S. residency for your partner if he or she is a foreigner. I could go on and on.
Unfortunately, both of the current presidential candidates are of the "Let them eat contracts" school, so the best we can hope for is action at the state level for now. But, for Heaven's sake, let's at least get it right at whatever level we can.