I probably like this book far better than it deserves; if so, it's because I imprinted on Heinlein's stuff during my formative years. At any rate, this novel is based on a terrific concept but suffers from flawed execution.
The concept: Johann Sebastian Bach Smith is ooooold. Oooooooooold. He's going to die soon. But he's also rich, and he wants to spend a huge chunk of his fortune having his brain transplanted into a younger body. This he does. ('Yea, though I walk through the valley of the shadow of death . . . ')
Well, the joke's on him. The body -- as he learns after the transplant is performed -- is not only female, it's the body of his beloved secretary Eunice Branca (who was killed in a mugging that conveniently left her in brain-transplantable condition, and who conveniently happened to have the very same rare blood type as old Smith). So Johann has to learn how to be female, and also has to get over feeling just terrible about taking over Eunice's body.
Ah, but the lucky fellow gets some help. Turns out Eunice's body is still inhabited by Eunice -- or maybe Smith is hallucinating her (perhaps as her body rejects the transplant?). Or maybe it doesn't matter which; reality is slippery that way. (' . . . I will fear no evil, for thou art with me.')
_Great_ concept. The idea alone is worthy of a Hugo.
Unfortunately, Hugos aren't given for ideas; they're given for execution. And the execution here is troubled.
Heinlein suffered from life-threatening peritonitis during this period of his life, and his wife Virginia had to help him out with the editing on this one. At that, Heinlein claimed to have trimmed the draft MS by some ungodly number of thousands of words, and the result is _still_ sort of saggy in places. Like, between the covers.
There are minor indications throughout that this isn't Heinlein's best-thought-out work. Here's my personal favorite example: when Johann, in Eunice's body, decides on a name, he suggests using 'Joan' but giving it the 'two-syllable pronunciation'. Apparently the author forgot that his character was _speaking_ the name, so that her listeners (who were not reading the text but hearing her speak) would _hear_ the two syllables; what they wouldn't know was how she intended to _spell_ it. (And what, by the way, would have been wrong with spelling it 'Joanne'? Then we wouldn't have had to worry about reader-vs.-listener at all, and I wouldn't have to keep reminding myself all the way through the blinkin' book that it's _not_ pronounced 'Jone'.)
Lots of the content is very dated, too. And it's not very realistic to imagine Joan Eunice spreadin' 'em for every big strong han'some male who treats her nice. (Including attorneys and judges, who might have had some ethical issues here. And please don't email me any lawyer jokes on the subject; believe me, I've heard 'em.)
But there's still lots of cool stuff. The dialogue (especially the _internal_ dialogue, of which there is naturally a long ton) is about as well handled as it could be. Eunice's 'stenodesk', allowing for time and fictional extrapolation, sure looks a lot like a modern desktop computer (in about the way that D.B. Davis's 'Drafting Dan' looked like a CAD system). There's also what must be one of SF's very first sympathetic fictional portraits of a same-sex couple.
So I still rate this one as a rewarding read (and in fact do reread it every now and again myself). It's not Heinlein's best; it's not even his second-tier material -- but it's still pretty darned good.
It's just not _great_. And that's too bad, because I'd have loved to see what Heinlein could have done with this concept had he been at the top of his game.