This is the teleological argument that god exists based on perceived evidence of order in the universe. The idea is that a watch requires a watchmaker and that the universe is vast and ordered and it requires a maker.
One flaw in this argument is that there is no single watchmaker. The analogy points to a watchmaker, but the watchmaker does not exist in a vaccuum. Many people's efforts are involved in the creation of a watch. Without other people's efforts (some as skilled as the watchmaker just in different fields) the watchmaker would be unable to make the watch. Continuing with this point, seldom does a watchmaker work alone, even back to the beginning of when we started making watches, as watchmakers would have apprentices. It would seem that if the watchmaker idea is worth anything it points to a mulitple god scenario, not a monotheistic god.
Another flaw is that the watchmaker doesn't make anything. An actual watchmaker takes the resources around him, the information or context around him and uses those parts and ideas to build a watch. It would seem that if this analogy is accurate then god assembled the universe from components around him and didn't create anything.