Ditto to what Caveat said. I painted the tiles in a bathroom. It's pretty labour intensive - wash with sugar soap, rinse off, two undercoats of tile paint, two overcoats of gloss.
IMHO, while it is fine for short-term covering horrible tiles, it fools no-one, looks amateurish and will start to fail after a while. Mine was done two years ago and is looking pretty worn. If I had to do it again I'd live with the tiles as they were and replace them as soon as I could afford them.