It's great in that it shows how certain things are more of a continuum than binary (like sexual orientation), but I also feel that the continuum and values they use for biological sex are wrong because it recognizes a "female self ID" and "male self ID" as a "biological sex" (i.e. gonads) value and I always thought that was related to "gender identity." It is my understanding that, with the exception of people who are born intersex and/or may have a genetic abnormality of the 23rd chromosome, all people have a binary biological sex, and for some it doesn't coincide with their gender identity/expression.
There's an updated version. But to comment on this piece: Your biological sex isn't completely determined by the presence (or lack) of the SRY gene though. And the reality is that the spectrum for biological sex is, in part, to describe intersex conditions, transsexual transitions, and the like. Intersex is no more homogenous as a group than bisexual. But here's the thing. If we really pay closer attention the biology of sex determinism, it is very complicated. Just having a functioning SRY gene doesn't mean you'll develop with male characteristics if your body doesn't react to androgens. The hormones themselves are super important in shaping the body in the uterus and during puberty. And how your body reacts is fairly unique to you. Are there sort of statistical things you can say about men and women after puberty? Sure. Men are more likely to develop facial hair, but it isn't unheard of in women. Women are more likely to have higher voices, but sometimes they drop quite a bit during puberty, while some men wind up not dropping very much. These secondary sex characteristics are still sex characteristics, and part of biological sex. And we tend to consider some of the possible variations (that don't get into the realm of Intersex) as conditions that the individual is expected to treat in some way, and dismiss them as such, rather than recognizing them as one of the ways one's biological sex will find themselves on a continuum rather than in a binary. V3 of the Genderbread Person makes this a bit more explicit by adding notes that call this stuff out. Now, if you want to go reductionist on this and say the important bits are in the gonads and genitals, and the rest aren't part of sex, then we're ignoring an awful lot of what sex hormones actually do to the body, and what we expect when it comes to the biological norms of a given sex.
There are so many different versions of these now. There is the genderbread person, the gender unicorn, and some others that I cannot find a decent image of. People create these charts to try to fix the "errors" of the previous charts. For example, a common complaint with the genderbread person is that the transgender symbol is over the area where sex organs are located. These things can be used as a tool, but often times they require some more explaining.
