The key is to put it on correctly. It will prevent chafing between your legs when you wear a skirt or dress, as no part of your inner thighs is exposed. You don't take it off to use the bathroom.
To put it on: pull the legs all the way up, and then extend them back down towards your knees, without twisting.
Buy the size you are, not the size you plan to be, and be prepared for a struggle. If you want something easy to put on, buy a size too big.