It seems that the fault here isn’t with Duckworth or Lewis, but whoever’s in charge of reading the calculations (in this case, coach John Dyson). It’s not an impossible task; I recall M.S. Dhoni saying after one match (against England, appropriately enough) that he kept a look on the necessary scores during a chase because he knew rain was coming, and India went on to win the match.
A Duckworth-Lewis calculator is available here; an explanation of the statistics behind the method can also be found via Wikipedia; a 1999 profile of Frank Duckworth and Tony Lewis can also be found from the Independent. My favorite part:
“Indecipherable, one paper called [the Duckworth-Lewis method],” says Duckworth. “They spelt it wrong too. People call it a `whim’. We would like people at least to try to understand it before saying it’s incomprehensible. You don’t have to be particularly numerate, no more so than filling in a tax form which everyone has to do now. You don’t need a university degree and you don’t need to be computer literate.”