Booking cruises on new ships

I would be interested in hearing about your experiences with booking a
cruise on a ship that is in the process of being built and and will
not be ready for a year or more. I know of people who had booked a
cruise, the ship was not ready on time, and they received a refund of
their money PLUS a free cruise when the ship was ready or on another
ship. I cannot find any place that actually gives the details of what
would happen if the ship is not ready. I imagine this may vary by
cruise lines. Also, is there some website that you can actually
follow the progress of a new ship as it is being built. I am
particularly interested the Celebrity ships. Thanks for your input.