what are the advantages and disavantages of humans having nails instead of claws on the ends of our man digit?

Advantage: Nails allow for more dexterity of the human hand.
Disadvantage: Claws are a good mean of defense against other animals.

It would be very hard to use tools which means things like tv and so on might not be here today, but if man had claws we might result to becoming omnivores!

We don't need claws for self-defense against other animals any more. We're 'civilized'. (If you can put it that way.)

But, if we were to grow our nails and sharpen them on rocks and such, they would be viable weapons for scratching and tearing at things.