Utena is just that complex that it's very easy for cursory identifications to give away important plot details. There are better works which deal with queer themes by Oniisama E 's artist, Ikeda Riyoko, but none are in my opinion amongst those which have been animated. The tropes Shimura tries to tackle are all those which have been previously mentioned in the above series, especially in Oniisama E and Marimite. This includes the idea that girls' high schools are overrun with lesbians and that lesbian or lesbian-like relationships commonly exist prior to marriage in these schools. Worth mentioning that Utena and Anthy are hardly the only potentially? Kazama Ushio on the right isn't shy about announcing that she's interested in other girls, and she often bemoans that homosexuality is still taboo in Japanese society. What puts this anime so far up on the list is that it's extremely well done for an anime series in general.
Is this a gay anime or an anime that appeals to girls?
The language, the style, the clothing, and the symbology are all "high" yuri, evoking imagery strongly associated with yuri history.
Watch this one at least twice. Above all, she is determined to unravel the mysteries of the prince and the setting around her. Only at seventeen do they choose a "permanent" sex, either male or female. While yuri subtext is pretty clear to many and is even clearer in the series' spin-off , Noir is just damn good fun where the focus is on an extremely strong relationship between the two female characters.