Aside from its cuteness, one thing I love about it is that it doesn't posit male and female, gay and straight or trans- and cis-gender as polar opposites, as many other models do. Although I know women and men are different in many ways, we also have many (perhaps many more) similarities, and are not necessarily from "Venus" or "Mars". Likewise, I realize that gay and straight are different, and so are trans and cis, but they are also not opposite poles in the world of sexuality and gender identity.
Instead, the model depicted seems to go from less sexuality to more, and from less gender-ness, if you will, to more.
It may not be the "right" model, but I think it makes more sense than the binaries about gender and sexuality we've been taught and that too many scholars, educators, and other often well-meaning people propogate, sometimes unwittingly.