If you read the post I linked above, you will read marlin's posts on downshifting. Mainly, where he says DON'T DO IT. Really, there is no advantage, other than getting really good at changing clutches. If you would rather change clutches and eventually a trans, then by all means downshift. I'd rather change brakes. Also, if you drive like a sane person and use the brakes rather than the trans to slow down, you will wind up learning to anticipate stops. Anticipating stops means slowing earlier, which means your brakes last longer too. Can't beat that deal.
On a side note, I do admit sometimes its cool to blip the gas or double clutch on the downshift. Just remember that it isn't necessary.
