From an economic standpoint, this tax cut is a decent but sub-optimal policy that is poorly timed, at least in textbook economics. But it is good politics, and in fact may be more positive than economists think if people still have a high aversion and resentment to paying the tax. However, we'll assume that the textbooks are correct and it is sub-optimal.
Remember that the Liberals were offering to cut taxes as well, so the macroeconomic consumer effect would have been more of less the same (though the Liberal policy was probably a bit better).
Most - but not all - of the time, its better to cut taxes than increase spending, given the level of government spending in Canada. But any tax cut should have been saved for a recession.
An income tax cut would have been more efficient. Taxing income distorts resource allocation more so than sales taxes because income taxes take resources out of consumers hands before the individual has allocated his resources to the source where he is most likely to optimize utility. Sales taxes do not cause this distorting effect since the individual is optimizing his utility at the point of purchase.
However, because the wealthy consume relatively less than the poor, taxes on consumption hurt the poor relatively more than the wealthy. You can design a system to lessen this effect - i.e. no tax on food or shelter - which alleviates this. But even after that, it is still likely to hurt people with less income than more.
EDIT - There are some on the Right in the US who are calling for an end to the income tax, and it being replaced by a sales/consumption tax.
