It would all be detrimental, since you stated whole chromosomes. It all has to do with dosage compensation of gene products. This is why even the double X chromosomes in females has to have one of the chromosomes be inactivated, so as not to cause detrimental effects to the organism. While the only X in the male (along with the Y chromosome) is fully activated.
Balance is the key. You can not have too little of one gene product and too much of a gene product.
@kolean
not necessarily. Yes in humans that is the case. But for example in plants poliploidy is often seemed and it has been a beneficial thing for plants in cold climates. And if you have an organism like an ophioglossum fern which has its genome divided between around n=600 chromosomes, an extra chromosome has so few genes that it may just be beneficial in some environments.
