Pros:

Most homes that have an upstairs and a downstairs build the bedrooms on the top floor and the entertaining, kitchen, living, and dining rooms on the main floor. Thus, one big pro of an upstairs laundry is that the laundry room is close to where the bedrooms are. This means no hauling of heavy baskets up and down stairs from the bedrooms to the laundry room. It basically means convenience and ease for whomever is doing the laundry. This alone is a big enough plus for many homeowners to say that despite the cons they are going to put their laundry room upstairs.

Other pros besides convenience include the fact that you can keep your laundry going during the day and not have to worry about the noise of the washing machine and dryer effecting company that may visit your home. Also, in the summer especially, running a dryer during the day can heat the house some. By having your dryer in an upstairs laundry the heat is not transferred through the whole house, rather since heat rises, only the ceiling of that top floor is affected.

An upstairs laundry is great for anyone with the desire to make their life more simple, and especially for those who want to entertain without putting their life on hold due to noise, etc. Having the laundry upstairs means you can excuse yourself for a few minutes, slip upstairs and out of the way, switch your load over, and then get back downstairs and back to entertaining.

So, with such convincing pros, what are the cons?

Cons include the face that upstairs laundry is generally more expensive. You would need extra drains in the floor to protect your house in case of any sort of laundry leaks. It also means the chance of any sort of leaks or floods caused by the washing machine causing damage to the rest of the house, or at least everything below. Flooding is one of the main problems with upstairs laundry rooms, and probably the biggest reason they are not in every home.
Another con many people do not consider is that believe it or not, having an upstairs laundry might even affect your insurance rates. Insurance companies have noted an increase in water damage claims associated with second floor laundries, and thus have often raised their insurance rates for those with homes that have this feature.

Last but not least, one of the cons of an upstairs laundry that may or may not be considered is that it limits the machines you can purchase to clean and dry your clothes. Believe it or not, there are some washers not recommended for upstairs laundry. For most this will not limit the selection of machines enough to make any sort of influence on their decision as to whether or not to put in an upstairs laundry, but for some, especially those that already own machines not recommended for upstairs laundry, this could be a very big deal.

If you are thinking about putting in an upstairs laundry, look at your lifestyle and weigh the pros and cons. Maybe instead of an upstairs laundry you can install a laundry chute and a dumb waiter to make your life easier and lighten your laundry carrying load. Often this produces the same desire effects for putting a laundry upstairs, without any of the negative side effects.