Their extinction was brought about so rapidly by the introduction of invasive species by seafarers, namely rats and pigs, which would eat the eggs from the ground nests of the dodo. This essentially devastated a population that had evolved in an environment with no such predators.

I've heard that they were also disgusting to eat - incredibly greasy, but first hand accounts by Dutch sailors occasionally refer to them in completely the opposite vein, as Heyndrick Dircksz Jolinck:

"we also found large birds, with wings as large as of a pigeon, so that they could not fly and were named penguins by the Portuguese. These particular birds have a stomach so large that it could provide two men with a tasty meal and was actually the most delicious part of the bird"

The following essay might prove interesting to you:

http://julianhume.co.uk/wp-content/uploads/2010/07/History-of-the-dodo-Hume.pdf