I don't usually read middlegrade books unless it's for personal nostalgia. But I was curious how a subject like being transgender is communicated to kids these days, so I picked up Alex Gino's Melissa which ended up being a pretty good, quick read.

I think Melissa overall does a good job at communicating a basic transgender experience to younger readers without going too much into the nitty-gritty complexities and keeping the conflicts to a necessary minimum. Yes, there are struggles. After all the protagonist is not coming out to anyone for a long time, and there is certainly some push-back from some adults and other kids, even if not always with bad intent. But the book doesn't dwell on these for too long and keeps the story lightweight, as well as populate it with plenty of supporting characters.
Part of me did wish it would confront some of these conflicts more aggressively or dive a bit deeper into certain aspects. I would have also personally liked a more critical view on the idea of binary gender as a whole. But I have to admit that it's probably a good idea to have a rather straight-forward and relatively easy story as an introduction to the subject for younger readers. There is time for the more complicated things later on.

There is some irony that this book was originally published under the title George, after what we would nowadays call the deadname of the protagonist Melissa. So now, many copies say "Melissa. Previously published as George".
The author added an FAQ to recent copies after the name-change about what's the deal with all that, which I thought was pretty reasonable. The protagonist is called George throughout most of the book (although pronouns are always she/her) until there is a key moment later from which on she is referred to as Melissa until the end of the book. So, yes, deadnaming is being taken more seriously these days. But as a stylistic choice to underline a turning point event in the protagonist's transition story, I thought it was a pretty effective decision to use both names of the protagonist.
As for the book title though, I think it should have been called Melissa from the beginning. The author says that it was originally supposed to be called Girl George, apparently as a bit of a nod to the musician Boy George, but the publisher wanted to simplify it to just George. Though eventually regret seeped in, and as awareness and sensibilities around the subject changed as well, the author made the choice to change the title. It's a bit awkward but there is something interesting about even the title of this book going through a gender transition in a way.

Anyway, Melissa is a comfortable, charming book that does a pretty good job at introducing a complex but timely subject to young people.