WARNING - Many assets in the NES Collection will not work on original hardware as there are sometimes more than 4 colours per 8x8 block, I've found some with 6 per 8x8. So if you are purchasing for authenticity or to actually to use on original NES hardware / emulators, be prepared to edit the artwork yourself like I am doing.
I think the assets look good, it is why I purchased the collection, and this collection will be fine without modification on a modern engine going for an 8-bit / NES look.