I tried this before (actually quite many years ago) and the result is pretty good. It is much cheaper as no hacking etc involved. But do note that there are dis-advantages: you can only spray on existing tiles (and even pipes!), but not wall; hence, if any change in the kitchen size will need to be carefully studied. Another more crucial point is about the water proof. Some renovation is done because of water leakage. As spraying is not going to renew the waterproof membrane, there is chance of water leakage. Some contractors said that for flats over 10 years life are better off to renew the water proof system.