The Grattan Institute has done a good job summarising the debate over income tax cuts:
Many of the core arguments appear contradictory: most of the tax cuts benefit high-income earners, yet some people argue that high-income earners will end up paying a higher share of tax. Some argue the tax cuts are needed to support the economic recovery, while others argue they won’t be effective or could even hinder the recovery.
This piece explains the main points of contention and why sensible people can come to such different conclusions.