You can't make soap suds in the shower! You get icky residue all over your sink and tub fixtures. Your washer isn't as efficient.
What are the disadvantages of hard water?
You shouldn't drink it, it is hard to clean with it (professional cleaners like http://www.deluxecleaners.co.uk/ use distilled water). It is even hard to clean after it has evaporated. If you have a steam iron use only distilled water. The same counts for other appliances that use steam or water.