We have prefinished hardwood. It's OK - it looks nice, etc. but the gaps between the boards are not as tight was site-finished hardwood. So it's possible for certain spills to get into the gaps and require a little extra cleaning.
With hardwood, there is site-finished and pre-finished.
With site-finished, they put down the unfinished wood, then sand, stain, and coat it. When we renovated our kitchen, we couldn't handle that - because of the way the house is laid out, we would have had to move out for a week while it was finished and that was not possible (school, pets, etc.)
With pre-finished, the wood is already stained etc. and they can just nail it down.
But the gaps between the boards are not quite as tight as site-finished.