For the love of all that is holy, before you buy a condo have someone go to the upstairs unit (or ask whoever lives there) and have them walk and run around and listen to the noise or you'll end up like me where you can't stand living in the biggest investment of your life.
Unless of course you're looking at a condo in Mahogany.... Then don't worry about it.... They're all great......
I'm actually legitimately worried that I won't be able to sell or rent it to anyone unless my upstairs neighbours move out and are replaced by people without kids, who walk light footed. It sucks.