I think January 1st was the phase-in for the new passport rules, but they keep getting pushed back so who knows. I do know that last year, having a passport greatly streamlined the process... we'd cross the border just to get to the duty free shop.
My experience at the border crossing near Glacier (port of Piegan) was that the Canadian guards are friendly and professional, whereas the US Customs goons made me feel like a criminal for trying to re-enter my own country.