Mugabe is a racist dictator and a thug. His policies are killing his countrymen and driving the country to ruin.
Taking land from the "whites" and giving it to the "blacks" doesn't do anything to make the average black Zimbabwean any better off. On the contrary it's going to make them worse off.
If left alone, the farmers would employ large numbers of black Zimbabweans. The farms would be run efficiently and would generate large amounts of foreign currency from sales of cash crops like tobacco or wheat. Those employed on the farms would be able to afford to feed their familes and have money over to spend on other necessities.
Instead the farms are to be handed over in small plots to the "blacks". And it's clear as day that they'll end up subsistence farming, struggling to make enough to live.
The wealth presently generated by that land will be reduced and none of those who get that land will end up any better off - except Mugabe and his friends who'll quietly acquire some more large farms of course.
The agenda behind this - like the Euro project - I feel another article coming ;-) is political not economic. White-bashing is the only way Mugabe can think of to try and convince his diminishing support that he's going to make their lives any better. When they realise that it's made them worse off I think he'll be booted out in a popular revolt - but not before thousands of Zimbabweans have died of starvation.