What is your opinion on cloning to reproduce endangered species and why?

I am watching a documentary about the work of an American scientist who is cloning endangered animals and using non-endangered animals as surrogates to carry the cloned cells. Should we use this technology to increase the numbers of endangered species? What about bringing back extinct animals? Do you want to see the Woolly Mammoth walking around the earth again? What about cloning Bengal Tigers to ensure they continue to exist? What are your thoughts about cloning for these reasons?