A few words on the Yale system.
It was developed in the first half of the 1940s, mainly by George Kennedy of Yale University. There is a brief but unusually frank biography of him here: www.umass.edu/wsp/methodology/gallery/kennedy.html . My website has an essay by him: “Fennolosa, Pound and the Chinese Character.” He was one of the earlier Western scholars to see through the myths about Chinese characters.
Kennedy, who also worked for the U.S. military at the time, developed the Yale romanization system for Mandarin with speakers of American English in mind. Like all other romanization systems for Mandarin, however, it must be learned to be used properly; there is no such thing as a “magic bullet” that will allow English speakers to naturally and without study pronounce Mandarin properly.
Taiwan’s own MPS2 romanization system is quite similar to the Yale system. MPS2, however, was supplanted as Taiwan’s official romanization system for Mandarin by Tongyong.
For a full comparison of Yale with other systems, see the chart on my site:
George A. Kennedy