I had mixed feelings about Malcolm. They could have done much more w the character. If the series had been more successful and had lasted longer, I think the Malcolm character would have been developed and explored to a much greater extent. That the series struggled really hampered the character development.
My own take is that Reed should have been the first officer and act as a counterpoint to Archers more idealestic approach. T'Pol shouldn't have been in the ships command structure and been there as an advisor only.