Just watched the final episode.
I totally appreciated this. I was also curious about the topic and how they would handle it. My first worry before seeing this was that it would turn the transgender topic into just another object of fanservice but it is clear from the very beginning that this show is quite serious about the subject. You can't really say Schuichi and Yoshino are just there to fulfil your hentai fantasies.
My second worry was that it would be transphobic and I really tried to pay attention to the clues it might give off. I'm glad I didn't find many of those (although I'm not so glad to find them on this thread...)
I'm not the right person to say whether this was realistic or not. Maybe if a transgendered person can relate to the characters it is? It would be quite a contrast to the wide range of shitty "LGBT" anime out there. I'm obviously refering to yuri and yaoi here, both of which often tend to be sexually objectifying, completely ignorant of gay issues and ironically homophobic