It also recognized slavery in the law, which hadn't been done before. On the one hand, this sucks. The worse alternative was that enslaved people had the same number of rights as inanimate property. HOWEVER

The Act Against Slavery was the law that meant that enslaved people who made it into Upper Canada were freed. It set the stage for the Underground Railroad and the emancipation of all those who could make it here. It was unambiguously a step forward. It is unambiguously worth celebrating.